Apple ID to share music
do family members on a family share plan sign in with their own Apple ID on their phone or with the person’s Apple ID that set up the family share plan?
iPhone XS, iOS 12
Question marked as
They must sign in with their own Apple ID. That's the point of the Family Plan. Each person is invited to the Family Group using their own Apple ID, so they can each have their own music library and can play music at the same time on their devices.
Apple ID's should not be shared for any reason.
See here for more details: Get an Apple Music Family subscription - Apple Support
