Consider the situation when you are treating this child for emotional or physical abuse by his own father (mom alleges). Even then you have to provide records to father if they have joint custody. It all depends on legal custody right. Mom has full custody and you violate it! Ouch!.
I had once a pt, his father was in jail for physically abusing this child, my Pt. And yet judge granted visitation rights to this criminal and mother had to take a kid to jail on schedule. Only in America.