Can You Legally Sell Horses That Have Been Abandoned On Property By Ex-husband?

So.. here’s the pickle my mom is in…

After her (currently ex-husband/once he is served to be ex husband) Is not originally from Canada, is from the states, a little over 3 years ago he over stayed his welcome in CAN during Covid and didn’t go back after his 6 month mark so he was forced to go back to the states and couldn’t return for a year or whatever it was. During that period of time he didn’t try very hard to rekindle anything or try to be a part of the family again. Including getting legal citizenship. This has caused a divorce to happen…Him and my mother have 4 horses together, his being 2. Fast forward a bit.. after little to no contact and my mom deciding to go through with the divorce, he will not cooperate with it so they’ll try and serve him. (Is what I understand). So during this time, my mom is getting ready to move from the place they were renting together. Through the lawyer, he was given a timeline of when she would be vacating that residence and that his horses would be there for him to pick up. (He had a month’s notice) He never came to grab them. So I trailered them to my mom’s new place because we weren’t going to dump them out there and leave them at the old place. She has been taking care of these two horses of his plus her own two (including feed, vet, farrier) without any money coming from him to help with any of this. He has not attempted to come collect his horses or voiced that he plans to. At this point I would assume they are technically owned by my mom now? Or is this not considered abandonment by the owner? Since it has been a little over a year of this. She fiscally cannot take care of these two horses plus her own for another year or more while we keep hoping he’ll want to come finally pick them up. (He ignores any contact from the lawyer regarding these things) Can we legally sell these horses? For my mom’s wellbeing, something needs to be done..

I hope all this is somewhat easy to follow, thank you and I apologize in advance haha..