diff --git a/packages/frontend-plugin-api/src/wiring/createExtensionBlueprint.test.tsx b/packages/frontend-plugin-api/src/wiring/createExtensionBlueprint.test.tsx
index dfdbfface6..5f1324fe7c 100644
--- a/packages/frontend-plugin-api/src/wiring/createExtensionBlueprint.test.tsx
+++ b/packages/frontend-plugin-api/src/wiring/createExtensionBlueprint.test.tsx
@@ -384,4 +384,70 @@ describe('createExtensionBlueprint', () => {
 
     expect(true).toBe(true);
   });
+
+  it('should allow merging of inputs', () => {
+    const blueprint = createExtensionBlueprint({
+      kind: 'test-extension',
+      attachTo: { id: 'test', input: 'default' },
+      inputs: {
+        test: createExtensionInput([coreExtensionData.routeRef], {
+          singleton: true,
+        }),
+      },
+      output: [coreExtensionData.reactElement.optional()],
+      factory(_params: { x?: string }, { inputs }) {
+        const ref: RouteRef = inputs.test.get(coreExtensionData.routeRef);
+
+        unused(ref);
+        return [];
+      },
+    });
+
+    blueprint.make({
+      inputs: {
+        test2: createExtensionInput([coreExtensionData.reactElement], {
+          singleton: true,
+        }),
+      },
+      factory(origFactory, { inputs }) {
+        const ref: RouteRef = inputs.test.get(coreExtensionData.routeRef);
+
+        const el: JSX.Element = inputs.test2.get(
+          coreExtensionData.reactElement,
+        );
+
+        unused(ref, el);
+
+        return origFactory({});
+      },
+    });
+
+    expect(true).toBe(true);
+  });
+
+  it('should not allow overriding inputs', () => {
+    const blueprint = createExtensionBlueprint({
+      kind: 'test-extension',
+      attachTo: { id: 'test', input: 'default' },
+      inputs: {
+        test: createExtensionInput([coreExtensionData.routeRef]),
+      },
+      output: [coreExtensionData.reactElement.optional()],
+      factory() {
+        return [];
+      },
+    });
+
+    blueprint.make({
+      inputs: {
+        // @ts-expect-error
+        test: createExtensionInput([]), // Overrides are not allowed
+      },
+      factory(origFactory) {
+        return origFactory({});
+      },
+    });
+
+    expect(true).toBe(true);
+  });
 });
diff --git a/packages/frontend-plugin-api/src/wiring/createExtensionBlueprint.ts b/packages/frontend-plugin-api/src/wiring/createExtensionBlueprint.ts
index 46db278bf8..90736703a0 100644
--- a/packages/frontend-plugin-api/src/wiring/createExtensionBlueprint.ts
+++ b/packages/frontend-plugin-api/src/wiring/createExtensionBlueprint.ts
@@ -83,7 +83,6 @@ export interface ExtensionBlueprint<
       { optional: boolean; singleton: boolean }
     >;
   },
-  UExtraOutput extends AnyExtensionDataRef,
   TConfig extends { [key in string]: unknown },
   TConfigInput extends { [key in string]: unknown },
   TDataRefs extends { [name in string]: AnyExtensionDataRef },
@@ -101,13 +100,23 @@ export interface ExtensionBlueprint<
       [key in string]: (zImpl: typeof z) => z.ZodType;
     },
     UFactoryOutput extends ExtensionDataValue<any, any>,
+    UExtraOutput extends AnyExtensionDataRef,
+    TExtraInputs extends {
+      [inputName in string]: ExtensionInput<
+        AnyExtensionDataRef,
+        { optional: boolean; singleton: boolean }
+      >;
+    },
   >(
     args: {
       namespace?: string;
       name?: string;
       attachTo?: { id: string; input: string };
       disabled?: boolean;
-      inputs?: TInputs;
+      inputs?: TExtraInputs & {
+        [KName in keyof TInputs]?: `Error: Input '${KName &
+          string}' is already defined in parent definition`;
+      };
       output?: Array<UExtraOutput>;
       config?: {
         schema: TExtensionConfigSchema & {
@@ -132,7 +141,7 @@ export interface ExtensionBlueprint<
                   ReturnType<TExtensionConfigSchema[key]>
                 >;
               };
-              inputs: Expand<ResolvedExtensionInputs<TInputs>>;
+              inputs: Expand<ResolvedExtensionInputs<TInputs & TExtraInputs>>;
             },
           ): Iterable<UFactoryOutput>;
         } & VerifyExtensionFactoryOutput<
@@ -172,7 +181,6 @@ class ExtensionBlueprintImpl<
       { optional: boolean; singleton: boolean }
     >;
   },
-  UExtraOutput extends AnyExtensionDataRef,
   TConfigSchema extends { [key in string]: (zImpl: typeof z) => z.ZodType },
   TDataRefs extends { [name in string]: AnyExtensionDataRef },
 > {
@@ -196,12 +204,22 @@ class ExtensionBlueprintImpl<
       [key in string]: (zImpl: typeof z) => z.ZodType;
     },
     UFactoryOutput extends ExtensionDataValue<any, any>,
+    UExtraOutput extends AnyExtensionDataRef,
+    TExtraInputs extends {
+      [inputName in string]: ExtensionInput<
+        AnyExtensionDataRef,
+        { optional: boolean; singleton: boolean }
+      >;
+    },
   >(args: {
     namespace?: string;
     name?: string;
     attachTo?: { id: string; input: string };
     disabled?: boolean;
-    inputs?: TInputs;
+    inputs?: TExtraInputs & {
+      [KName in keyof TInputs]?: `Error: Input '${KName &
+        string}' is already defined in parent definition`;
+    };
     output?: Array<UExtraOutput>;
     params?: TParams;
     config?: {
@@ -228,7 +246,7 @@ class ExtensionBlueprintImpl<
         } & {
           [key in keyof TConfigSchema]: z.infer<ReturnType<TConfigSchema[key]>>;
         };
-        inputs: Expand<ResolvedExtensionInputs<TInputs>>;
+        inputs: Expand<ResolvedExtensionInputs<TInputs & TExtraInputs>>;
       },
     ): Iterable<UFactoryOutput>;
   }): ExtensionDefinition<
@@ -277,7 +295,7 @@ class ExtensionBlueprintImpl<
       name: args.name ?? name,
       attachTo: args.attachTo ?? this.options.attachTo,
       disabled: args.disabled ?? this.options.disabled,
-      inputs: args.inputs ?? this.options.inputs,
+      inputs: { ...args.inputs, ...this.options.inputs },
       output: [...(args.output ?? []), ...this.options.output],
       config: Object.keys(schema).length === 0 ? undefined : { schema },
       factory: ({ node, config, inputs }) => {
@@ -297,7 +315,7 @@ class ExtensionBlueprintImpl<
               return this.options.factory(innerParams, {
                 node,
                 config: innerContext?.config ?? config,
-                inputs: innerContext?.inputs ?? inputs,
+                inputs: (innerContext?.inputs ?? inputs) as any, // TODO: Fix the way input values are overridden
               });
             },
             {
@@ -317,7 +335,7 @@ class ExtensionBlueprintImpl<
       },
     } as CreateExtensionOptions<
       UOutput,
-      TInputs,
+      TInputs & TExtraInputs,
       {
         [key in keyof TExtensionConfigSchema]: z.infer<
           ReturnType<TExtensionConfigSchema[key]>
@@ -357,7 +375,6 @@ export function createExtensionBlueprint<
       { optional: boolean; singleton: boolean }
     >;
   },
-  UExtraOutput extends AnyExtensionDataRef,
   TConfigSchema extends { [key in string]: (zImpl: typeof z) => z.ZodType },
   UFactoryOutput extends ExtensionDataValue<any, any>,
   TDataRefs extends { [name in string]: AnyExtensionDataRef } = never,
@@ -374,7 +391,6 @@ export function createExtensionBlueprint<
   TParams,
   UOutput,
   TInputs,
-  UExtraOutput,
   string extends keyof TConfigSchema
     ? {}
     : { [key in keyof TConfigSchema]: z.infer<ReturnType<TConfigSchema[key]>> },
@@ -391,7 +407,6 @@ export function createExtensionBlueprint<
     TParams,
     UOutput,
     TInputs,
-    UExtraOutput,
     string extends keyof TConfigSchema
       ? {}
       : {