What is the ruling on a mother severing ties with her sister (the aunt) and ordering her children to sever ties with her, because the aunt rejected the mother's advice regarding her daughter and some reprehensible matters, knowing that it was the aunt who requested the severing of ties?

Maintaining kinship ties is obligatory, and severing them is forbidden. It was not appropriate for the aunt (maternal) to boycott her sister simply because she reminded her of Allah, for a believer is reminded when Allah is mentioned, and does not become angry or agitated. The mother should respond to this behavior with patience and forbearance, and not return evil with evil. She should also not order her children to boycott their aunt, for there is no obedience to a creature in disobedience to the Creator. As for you, children, maintain ties with your aunt as much as you can. If the mother insists on her stance, you can maintain ties with your aunt without her knowledge. If the aunt insists on the boycott, you can suffice with inquiring about her by phone.