On the App Store certain items like in-app purchases and subscriptions to most services cannot be shared with the Family Sharing feature. You can read more information on what can and can't be shared with this system here: https://support.apple.com/en-us/HT203046
In-app purchases and most subscriptions are attached to an account, but not a device. Buying an in-app purchase like a new area in Dr. Panda Town or recipe in Dr. Panda Cafe: Freemium will unlock them on all devices this purchasing account is used on, but these cannot be shared to different accounts. One thing which can work, is to log in to the App Store account that made the purchase on the iPad or iPhone you want to unlock the content on, open the app, and tap "restore purchases" on the in-app purchase window. This will unlock the content in that app on that device.