Responses
The worse one out of this IS the girls' mother. I mean the father is a shit. But his decision to push on the girls to their brother was in their interest. Since, the dad had NO means to provide any stability for the girls. The mother of the girls knew this and she still abandoned the girls and used her new lover as a scapegoat.
The mother literally thought of herself first and foremost. Couldn't care about what was best for the girls.
Srsly the way I would cut them off he's being too accommodating. I know the kids still like the father and that's fine, he can visit for them but he shouldn't be trying to reenter the son's life like that. Keep your distance