Does iOS8 Family Sharing allow to share In-App Purchases?

Solution 1:

In App purchases are not shared in Family sharing and its clearly given in apple website. But what we can do is log in to iTunes & App store using the ID which was used to buy the in app purchases without having to change the primary ID of the device and still enjoy the in app purchases

Solution 2:

Apple does not include In-App purchases on their site, meaning they are not included. If In-App purchases would be shared, it would have been stated there very clearly.

Once you set up Family Sharing, family members get immediate access to each other’s music, movies, TV shows, books, and apps.

You can see the official page here.

Personal note: I don't see In-App purchases being shared soon or in the near future as they include lifes for games for example.