The Family Share program doesn't allow the sharing of in-app purchases. For more information follow this link: https://support.apple.com/HT203046   

 

Therefore, to be able to share them, you must do the following in each of the devices with blocked access to the in-app purchases: 

1. Uninstall the app from the device. 

2. Exit the Apple account, tapping: Settings, in the device's menu > Apple ID> Sign Out. 

3. Log onto the Apple account that made the in-app purchase: insert your Apple ID and Password > tap Sign In. 

4. Download the app again. 

5. Open the app and enter the in-app Settings (gear icon or "i" icon > tap the "Restore Purchases" button. 

6. There! The packs should now be unlocked.   

 

Once the purchases have been unlocked repeat steps 2 and 3 to change the Apple ID back to the one held by the person who uses the device.