Child Benefit for young mum in care

Has anyone come across this scenario before?

I’ve been asked whether a young mother can claim Child Benefit.  The young lady is a 15 year old looked after child.  Her baby is also technically a looked after child as she is subject to an interim care order, however the mum and baby reside together in a mother and baby assessment unit.  Social Services are funding the placement - it sounds as if it is a residential home as the social worker says the young lady doesn’t have to pay any rent or service charges.

Looking at the Child Benefit rules I think she could argue that the child lives with her for more than two consecutive nights per week, so she is entitled to claim even though the child is looked after.  But on the other hand, there’s no entitlement to child benefit if a child has been placed by a local authority and the local authority is paying towards their accommodation or maintenance. 

Given that the local authority is funding the placement, and will also be giving the young lady money for living expenses at least until she is 16 and able to claim UC, what are Child Benefit likely to decide?  Or alternatively, what should they decide?