What is the ruling on someone who leads people in prayer by force, knowing that there is a regular imam?

The resident Imam has more right to lead the prayer than others. It is forbidden for anyone to lead people in prayer in a mosque that has a resident Imam except with his permission, because he is in the position of the master of the house and has more right to it, and because [leading without his permission] leads to alienating people from him. If someone other than the resident Imam does so without his permission, his prayer is invalid according to many Hanbalis.