Can executor add their name to a dead’s person deed, and make it like the property was given to them without the deceased signing it over to them.

My mother passed 3yrs ago. In her will my brother is executor, my niece is second executor, and my sister is trustee. After her death my brother is the one to manage the estate. Since then he has been trying to kick me and my kids out the house. I have been living in the house with my mother and kids before her death. Before she died she stated that her grandchildren is to stay and finish school til the are out of high school. She even signed an legal document that stated this is our permanent address. With that said my brother knows this. But since he was named executor of the will he’s been selfish about what her wishes were. There is no lease attached to the house. We don’t pay rent and we never did with her. He has tried to get rent out us since her death. Also he added his name to the deed a year after she died. When I got the copy of the deed it look like my brother sold the property to himself for a $1.00. She never signed anything transferring the deed to him. Is this legal.