In the same subject.
I tried to use a family members CC (permissible) for my iTunes account for Apple Music (which requires a CC on file even though no charges will be added until the 3 month trial is up). I added it and got the free trial started, when I removed their CC, no music would play, so I tried re-adding it to my account and I got a error saying the card was declined. Whats the reason for this? How could a $0.00 purchase be declined?