How to associate a new Windows Phone app to an existing Windows Store app
See Create your app info for more information about app names and associating your Windows Phone app with a Windows Store app.
Associating a new Windows Phone app with an existing Windows Store app
In your Windows Phone Dev Center Dashboard, click Submit app.
Click App info.
In the Name field, in the App name section, select the Windows Store app you want to link to your Windows Phone app.
Click Associate app.
Add other required app information, such as description, packages, and so on.
Submit the new app.