I'm guessing this smaller adolescent bear that has moved in is a cub from years ago or related to the momma bear. She's not chasing him out of the territory and he's allowed to get close to her new cubs.
I never saw a young bear or cub with Momma bear last year though.
Momma bear sure has put on weight since last year. Glad to see it. Her cubs are putting on weight too. I was worried one of them had died since I didn't see it in photos and video last week, but looks like everyone is healthy.