Insurance Question!!*

Okay so my mom and her husband are getting a divorce and he bought took her out a car a while ago and then he took himself out one. My mom's name was on the registration for the car but someone he took her name off the registration? Is that possible without my mom signing anything? We lived in Canada and I was very curious about this but this racket has been going back and forth a while now. (he's trying to get the car to just get revenge on my mom because she called the police on him)