Maintenance,custody and divorce

Slms respected Elder

I require information regarding the following:
At what age does a girl who has become baaligh and the mother refuses to even allow me (the biological) father to see my child. Yet she still demands for maintenance.
The husband who is a moulana in durban beachfront masjid says he has nothing to do about it but yet she stays with him, (non-mahram).
The mother does not even allow my daughter to remove her nikaab in front of me. Now this moulana and his wife are propagting a divorce for my eldest daughter and he says he will allow her to stay under his roof. She is pregnant and they are now demanding conditions from her husband before she returns to her husbands home. Please assist with a reply and refer me to the relevant department for assistance for both matters.

Jazakallah