Uh, if we're complaining about the guy's Mom getting involved, how can we tell Duel to go there?
I say tell the girls they need to police their own relationships. Maybe offer up some low key advice, but I would seriously downplay the whole thing and softly chuckle (so the girls can see you do it) at the guy falling apart and Mommy driving him home.
We ALL know there are better men out there for the girls. It's getting THEM to realize it and take charge of their own affairs. Duel, YOUR girl needs to take the high road on this. In 2 years, it won't mean a damned thing what "Johnny" (whaever the tool's name is) says over the next month. Won't they be home for summer then? It's amazing what a summer away will do for them all.
Now if the guy escalates the issue and begins to harass her, I'd prob get the school involved and document the hell out of every step. Then again, Duel's a atty. (now I have that video Gogar made in my head)
Btw, post a new pic of the girls.