diff --git a/packages/flutter_availability/lib/src/service/availability_service.dart b/packages/flutter_availability/lib/src/service/availability_service.dart
index cea7b60..557a424 100644
--- a/packages/flutter_availability/lib/src/service/availability_service.dart
+++ b/packages/flutter_availability/lib/src/service/availability_service.dart
@@ -1,4 +1,6 @@
+import "package:flutter/material.dart";
 import "package:flutter_availability_data_interface/flutter_availability_data_interface.dart";
+import "package:rxdart/rxdart.dart";
 
 ///
 class AvailabilityService {
@@ -13,4 +15,108 @@ class AvailabilityService {
 
   ///
   final AvailabilityDataInterface dataInterface;
+
+  /// Creates a set of availabilities for the given [range], where every
+  /// availability is a copy of [availability] with only date information
+  /// changed
+  Future<void> createAvailability(
+    AvailabilityModel availability,
+    DateTimeRange range,
+  ) async {
+    await dataInterface.createAvailabilitiesForUser(
+      userId: userId,
+      availability: availability,
+      start: range.start,
+      end: range.end,
+    );
+  }
+
+  /// Returns a stream where data from availabilities and templates are merged
+  Stream<List<AvailabilityWithTemplate>> getOverviewDataForMonth(
+    DateTime dayInMonth,
+  ) {
+    var start = DateTime(dayInMonth.year, dayInMonth.month);
+    var end = DateTime(start.year, start.month + 1, 0);
+
+    var availabilityStream = dataInterface.getAvailabilityForUser(
+      userId: userId,
+      start: start,
+      end: end,
+    );
+
+    return availabilityStream.switchMap((availabilities) {
+      var templateIds = availabilities
+          .map((availability) => availability.templateId)
+          .whereType<String>()
+          .toSet()
+          .toList();
+
+      var templatesStream = dataInterface.getTemplatesForUser(
+        userId: userId,
+        templateIds: templateIds,
+      );
+
+      List<AvailabilityWithTemplate> combineTemplateWithAvailability(
+        List<AvailabilityModel> availabilities,
+        List<AvailabilityTemplateModel> templates,
+      ) {
+        // create a map to reduce lookup speed to O1
+        var templateMap = {
+          for (var template in templates) ...{
+            template.id: template,
+          },
+        };
+
+        return [
+          for (var availability in availabilities) ...[
+            AvailabilityWithTemplate(
+              availabilityModel: availability,
+              template: templateMap[availability.templateId],
+            ),
+          ],
+        ];
+      }
+
+      return Rx.combineLatest2(
+        Stream.value(availabilities),
+        templatesStream,
+        combineTemplateWithAvailability,
+      );
+    });
+  }
+}
+
+/// A combination of availability and template for a single day
+class AvailabilityWithTemplate {
+  /// Creates
+  const AvailabilityWithTemplate({
+    required this.availabilityModel,
+    required this.template,
+  });
+
+  /// the availability
+  final AvailabilityModel availabilityModel;
+
+  /// the related template, if any
+  final AvailabilityTemplateModel? template;
+}
+
+/// Extension to retrieve all unique templates from a combined list
+extension RetrieveUniqueTemplates on List<AvailabilityWithTemplate> {
+  /// Retrieve all unique templates from a combined list
+  List<AvailabilityTemplateModel> getUniqueTemplates() =>
+      map((entry) => entry.template)
+          .whereType<AvailabilityTemplateModel>()
+          .fold(
+        <AvailabilityTemplateModel>[],
+        (current, template) {
+          if (!current.any((other) => other.id == template.id)) {
+            return [
+              ...current,
+              template,
+            ];
+          }
+          return current;
+        },
+      );
 }
diff --git a/packages/flutter_availability/lib/src/service/local_data_interface.dart b/packages/flutter_availability/lib/src/service/local_data_interface.dart
index 2cdd4f7..7b93472 100644
--- a/packages/flutter_availability/lib/src/service/local_data_interface.dart
+++ b/packages/flutter_availability/lib/src/service/local_data_interface.dart
@@ -3,17 +3,24 @@ import "dart:async";
 import "package:flutter_availability_data_interface/flutter_availability_data_interface.dart";
 
 /// A local implementation of the [AvailabilityDataInterface] that stores data
-///  in memory.
+/// in memory.
 class LocalAvailabilityDataInterface implements AvailabilityDataInterface {
   final Map<String, List<AvailabilityModel>> _userAvailabilities = {};
+  final Map<String, List<AvailabilityTemplateModel>> _userTemplates = {};
 
   final StreamController<Map<String, List<AvailabilityModel>>>
       _availabilityController = StreamController.broadcast();
+  final StreamController<Map<String, List<AvailabilityTemplateModel>>>
+      _templateController = StreamController.broadcast();
 
-  void _notifyChanges() {
+  void _notifyAvailabilityChanges() {
     _availabilityController.add(_userAvailabilities);
   }
 
+  void _notifyTemplateChanges() {
+    _templateController.add(_userTemplates);
+  }
+
   @override
   Future<List<AvailabilityModel>> applyTemplateForUser(
     String userId,
@@ -21,29 +28,54 @@ class LocalAvailabilityDataInterface implements AvailabilityDataInterface {
     DateTime start,
     DateTime end,
   ) async {
-    // Implementation for applying a template
-    throw UnimplementedError();
+    var availabilities = template.apply(start, end);
+    _userAvailabilities.putIfAbsent(userId, () => []).addAll(availabilities);
+    _notifyAvailabilityChanges();
+    return availabilities;
   }
 
   @override
-  Future<AvailabilityModel> createAvailabilityForUser(
-    String userId,
-    AvailabilityModel availability,
-  ) async {
+  Future<void> createAvailabilitiesForUser({
+    required String userId,
+    required AvailabilityModel availability,
+    required DateTime start,
+    required DateTime end,
+  }) async {
     var availabilities = _userAvailabilities.putIfAbsent(userId, () => []);
-    var newAvailability = availability.copyWith(id: _generateId());
-    availabilities.add(newAvailability);
-    _notifyChanges();
-    return newAvailability;
+
+    var templateData = DayTemplateData(
+      startTime: availability.startDate,
+      endTime: availability.endDate,
+      breaks: availability.breaks,
+    );
+
+    var newAvailabilities = templateData.apply(
+      start: start,
+      end: end,
+      userId: userId,
+    );
+
+    for (var newAvailability in newAvailabilities) {
+      availabilities.add(
+        newAvailability.copyWith(
+          id: _generateId(),
+        ),
+      );
+    }
+
+    _notifyAvailabilityChanges();
   }
 
   @override
   Future<AvailabilityTemplateModel> createTemplateForUser(
     String userId,
     AvailabilityTemplateModel template,
-  ) {
-    // Implementation for creating a template
-    throw UnimplementedError();
+  ) async {
+    var templates = _userTemplates.putIfAbsent(userId, () => []);
+    var newTemplate = template.copyWith(id: _generateId());
+    templates.add(newTemplate);
+    _notifyTemplateChanges();
+    return newTemplate;
   }
 
   @override
@@ -55,14 +87,17 @@ class LocalAvailabilityDataInterface implements AvailabilityDataInterface {
     if (availabilities != null) {
       availabilities
           .removeWhere((availability) => availability.id == availabilityId);
-      _notifyChanges();
+      _notifyAvailabilityChanges();
     }
   }
 
   @override
-  Future<void> deleteTemplateForUser(String userId, String templateId) {
-    // Implementation for deleting a template
-    throw UnimplementedError();
+  Future<void> deleteTemplateForUser(String userId, String templateId) async {
+    var templates = _userTemplates[userId];
+    if (templates != null) {
+      templates.removeWhere((template) => template.id == templateId);
+      _notifyTemplateChanges();
+    }
   }
 
   @override
@@ -109,16 +144,32 @@ class LocalAvailabilityDataInterface implements AvailabilityDataInterface {
   Stream<AvailabilityTemplateModel> getTemplateForUserById(
     String userId,
     String templateId,
-  ) {
-    // Implementation for getting a template by ID
-    throw UnimplementedError();
-  }
+  ) =>
+      _templateController.stream.map((templatesMap) {
+        var templates = templatesMap[userId];
+        if (templates != null) {
+          return templates.firstWhere((template) => template.id == templateId);
+        } else {
+          throw Exception("Template not found");
+        }
+      });
 
   @override
-  Stream<List<AvailabilityTemplateModel>> getTemplatesForUser(String userId) {
-    // Implementation for getting all templates for a user
-    throw UnimplementedError();
-  }
+  Stream<List<AvailabilityTemplateModel>> getTemplatesForUser({
+    required String userId,
+    List<String>? templateIds,
+  }) =>
+      _templateController.stream.map((templatesMap) {
+        var templates = templatesMap[userId];
+        if (templateIds != null) {
+          return templates
+                  ?.where((template) => templateIds.contains(template.id))
+                  .toList() ??
+              [];
+        } else {
+          return templates ?? [];
+        }
+      });
 
   @override
   Future<AvailabilityModel> updateAvailabilityForUser(
@@ -132,7 +183,7 @@ class LocalAvailabilityDataInterface implements AvailabilityDataInterface {
           .indexWhere((availability) => availability.id == availabilityId);
       if (index != -1) {
         availabilities[index] = updatedModel.copyWith(id: availabilityId);
-        _notifyChanges();
+        _notifyAvailabilityChanges();
         return availabilities[index];
       }
     }
@@ -144,10 +195,20 @@ class LocalAvailabilityDataInterface implements AvailabilityDataInterface {
     String userId,
     String templateId,
     AvailabilityTemplateModel updatedModel,
-  ) {
-    // Implementation for updating a template
-    throw UnimplementedError();
+  ) async {
+    var templates = _userTemplates[userId];
+    if (templates != null) {
+      var index = templates.indexWhere((template) => template.id == templateId);
+      if (index != -1) {
+        templates[index] = updatedModel.copyWith(id: templateId);
+        _notifyTemplateChanges();
+        return templates[index];
+      }
+    }
+    throw Exception("Template not found");
   }
 
-  String _generateId() => DateTime.now().millisecondsSinceEpoch.toString();
+  int _id = 1;
+
+  String _generateId() => (_id++).toString();
 }
diff --git a/packages/flutter_availability/lib/src/ui/screens/template_availability_day_overview.dart b/packages/flutter_availability/lib/src/ui/screens/template_availability_day_overview.dart
index 7bc03f3..be15326 100644
--- a/packages/flutter_availability/lib/src/ui/screens/template_availability_day_overview.dart
+++ b/packages/flutter_availability/lib/src/ui/screens/template_availability_day_overview.dart
@@ -124,9 +124,11 @@ class _AvailabilityDayOverviewState extends State<AvailabilityDayOverview> {
         }
       } else {
         // add an availability for the user
-        await service.dataInterface.createAvailabilityForUser(
-          userId,
-          _availability,
+        await service.dataInterface.createAvailabilitiesForUser(
+          userId: userId,
+          availability: _availability,
+          start: widget.date,
+          end: widget.date,
         );
       }
       if (context.mounted) {
diff --git a/packages/flutter_availability/lib/src/ui/widgets/default_base_screen.dart b/packages/flutter_availability/lib/src/ui/widgets/default_base_screen.dart
index 08e745e..9bbb11f 100644
--- a/packages/flutter_availability/lib/src/ui/widgets/default_base_screen.dart
+++ b/packages/flutter_availability/lib/src/ui/widgets/default_base_screen.dart
@@ -3,12 +3,12 @@ import "package:flutter_availability/src/util/scope.dart";
 
 /// Default base screen for any availability screen
 class DefaultBaseScreen extends StatelessWidget {
-
   /// Create a base screen
   const DefaultBaseScreen({
     required this.child,
     super.key,
   });
+
   /// Builder as default option
   static Widget builder(
     BuildContext context,
diff --git a/packages/flutter_availability/lib/src/util/scope.dart b/packages/flutter_availability/lib/src/util/scope.dart
index c575d8f..7fd92b4 100644
--- a/packages/flutter_availability/lib/src/util/scope.dart
+++ b/packages/flutter_availability/lib/src/util/scope.dart
@@ -2,9 +2,9 @@ import "package:flutter/widgets.dart";
 import "package:flutter_availability/src/config/availability_options.dart";
 import "package:flutter_availability/src/service/availability_service.dart";
 
-/// 
+///
 class AvailabilityScope extends InheritedWidget {
-  /// 
+  ///
   const AvailabilityScope({
     required this.userId,
     required this.options,
@@ -12,10 +12,13 @@ class AvailabilityScope extends InheritedWidget {
     required super.child,
     super.key,
   });
+
   ///
   final String userId;
+
   ///
   final AvailabilityOptions options;
+
   ///
   final AvailabilityService service;
 
diff --git a/packages/flutter_availability/pubspec.yaml b/packages/flutter_availability/pubspec.yaml
index d725a03..4baee3e 100644
--- a/packages/flutter_availability/pubspec.yaml
+++ b/packages/flutter_availability/pubspec.yaml
@@ -11,6 +11,7 @@ dependencies:
   flutter:
     sdk: flutter
   intl: any
+  rxdart: ^0.28.0
   flutter_availability_data_interface:
     git:
       url: https://github.com/Iconica-Development/flutter_availability
@@ -19,6 +20,7 @@ dependencies:
 dev_dependencies:
   flutter_test:
     sdk: flutter
+  mocktail: ^1.0.4
   flutter_iconica_analysis:
     git:
       url: https://github.com/Iconica-Development/flutter_iconica_analysis
diff --git a/packages/flutter_availability/test/mocks.dart b/packages/flutter_availability/test/mocks.dart
new file mode 100644
index 0000000..f73eaad
--- /dev/null
+++ b/packages/flutter_availability/test/mocks.dart
@@ -0,0 +1,8 @@
+import "package:flutter_availability_data_interface/flutter_availability_data_interface.dart";
+import "package:mocktail/mocktail.dart";
+
+class DataInterfaceMock extends Mock implements AvailabilityDataInterface {}
+
+class MockTemplate extends Mock implements AvailabilityTemplateModel {}
+
+class MockAvailability extends Mock implements AvailabilityModel {}
diff --git a/packages/flutter_availability/test/service/availability_service_test.dart b/packages/flutter_availability/test/service/availability_service_test.dart
new file mode 100644
index 0000000..43b9266
--- /dev/null
+++ b/packages/flutter_availability/test/service/availability_service_test.dart
@@ -0,0 +1,102 @@
+import "package:flutter_availability/src/service/availability_service.dart";
+import "package:flutter_test/flutter_test.dart";
+import "package:mocktail/mocktail.dart";
+
+import "../mocks.dart";
+
+const String testUserId = "test_user";
+
+void main() {
+  group("AvailabilityService", () {
+    late AvailabilityService sut;
+    late DataInterfaceMock dataInterfaceMock;
+
+    setUp(() {
+      dataInterfaceMock = DataInterfaceMock();
+      sut = AvailabilityService(
+        userId: testUserId,
+        dataInterface: dataInterfaceMock,
+      );
+    });
+
+    group("getOverviewDataForMonth", () {
+      test("should combine availabilities and relating templates", () {
+        var dateTime = DateTime(2012, 12);
+        var templateId = "1";
+
+        var availabilityModel1 = MockAvailability();
+        when(() => availabilityModel1.templateId).thenReturn(templateId);
+        var availabilityModel2 = MockAvailability();
+        when(() => availabilityModel2.templateId).thenReturn(templateId);
+
+        when(
+          () => dataInterfaceMock.getAvailabilityForUser(
+            userId: any(named: "userId"),
+            start: any(named: "start"),
+            end: any(named: "end"),
+          ),
+        ).thenAnswer(
+          (_) => Stream.value([
+            availabilityModel1,
+            availabilityModel2,
+          ]),
+        );
+
+        var template1 = MockTemplate();
+        when(() => template1.id).thenReturn(templateId);
+        var template2 = MockTemplate();
+        when(() => template2.id).thenReturn("other");
+        when(
+          () => dataInterfaceMock.getTemplatesForUser(
+            userId: any(named: "userId"),
+            templateIds: any(named: "templateIds"),
+          ),
+        ).thenAnswer(
+          (_) => Stream.value([
+            template1,
+            template2,
+          ]),
+        );
+
+        var resultingStream = sut.getOverviewDataForMonth(dateTime);
+
+        expect(
+          resultingStream,
+          emits(
+            isA<List<AvailabilityWithTemplate>>()
+                .having((e) => e.length, "has two values", equals(2))
+                .having(
+                  (e) => e,
+                  "Contains availability 1",
+                  contains(
+                    predicate<AvailabilityWithTemplate>(
+                      (e) => e.availabilityModel == availabilityModel1,
+                    ),
+                  ),
+                )
+                .having(
+                  (e) => e,
+                  "Contains template 1",
+                  contains(
+                    predicate<AvailabilityWithTemplate>(
+                      (e) => e.template == template1,
+                    ),
+                  ),
+                )
+                .having(
+                  (e) => e,
+                  "Does not contain template 2",
+                  isNot(
+                    contains(
+                      predicate<AvailabilityWithTemplate>(
+                        (e) => e.template == template2,
+                      ),
+                    ),
+                  ),
+                ),
+          ),
+        );
+      });
+    });
+  });
+}
diff --git a/packages/flutter_availability_data_interface/lib/src/data_interface.dart b/packages/flutter_availability_data_interface/lib/src/data_interface.dart
index 56bab9e..52359fe 100644
--- a/packages/flutter_availability_data_interface/lib/src/data_interface.dart
+++ b/packages/flutter_availability_data_interface/lib/src/data_interface.dart
@@ -38,16 +38,21 @@ abstract interface class AvailabilityDataInterface {
   );
 
   /// Creates a new persistant representation of an availability model.
-  Future<AvailabilityModel> createAvailabilityForUser(
-    String userId,
-    AvailabilityModel availability,
-  );
+  Future<void> createAvailabilitiesForUser({
+    required String userId,
+    required AvailabilityModel availability,
+    required DateTime start,
+    required DateTime end,
+  });
 
   /// Retrieves a list of templates for the given [userId].
   ///
   /// Whether this is a one time value or a continuous stream of values is up to
   /// the implementation.
-  Stream<List<AvailabilityTemplateModel>> getTemplatesForUser(String userId);
+  Stream<List<AvailabilityTemplateModel>> getTemplatesForUser({
+    required String userId,
+    List<String>? templateIds,
+  });
 
   /// Retrieves a specific template for the given
   /// [userId] and [templateId]
diff --git a/packages/flutter_availability_data_interface/lib/src/models/templates.dart b/packages/flutter_availability_data_interface/lib/src/models/templates.dart
index 55fc5f9..0bd7a5e 100644
--- a/packages/flutter_availability_data_interface/lib/src/models/templates.dart
+++ b/packages/flutter_availability_data_interface/lib/src/models/templates.dart
@@ -76,6 +76,25 @@ class AvailabilityTemplateModel {
         end: end,
         templateId: id,
       );
+
+  /// Copies the current properties into a new
+  /// instance of [AvailabilityTemplateModel],
+  AvailabilityTemplateModel copyWith({
+    String? id,
+    String? userId,
+    String? name,
+    int? color,
+    AvailabilityTemplateType? templateType,
+    TemplateData? templateData,
+  }) =>
+      AvailabilityTemplateModel(
+        id: id ?? this.id,
+        userId: userId ?? this.userId,
+        name: name ?? this.name,
+        color: color ?? this.color,
+        templateType: templateType ?? this.templateType,
+        templateData: templateData ?? this.templateData,
+      );
 }
 
 /// Used as the key for defining week-based templates