I am currently developing an iOS software that might share data between devices through iCloud Data. It is meant to be used between family members, as such, it seems a match in heaven with Family Sharing. But there doesn't seem to be any way to tell whether these two persons are from the same family, or at least that their devices seems to know each other. I don't want to ask for special permissions to the user such as contacts access, and I frown adding weirdo things such as sharing stuff in the Family Calendar only to test if they are the same.
I don't mind false positives either, but I wish to remove the idea of a hacker from a faraway land asking for permission, or a malicious Ex somewhere that tries to access what they shouldn't.
Any ideas?
