I'm so glad that he's getting cooperation from the school.
I used to actually prefer separate meetings - only because my husband and the girls' mom were so contentious and she was so passive aggressive, it became about them and a contest who was the bad/better parent. Once they were able to get past that a little bit, they've become far better at sitting in the same room.
Teachers are also becoming more and more accustomed to these kinds of arrangements and are pretty accommodating.
Allow the kids to be the focus.

Also, the pwBPD in our life is awful with paperwork so my husband has become really handy at taking care of that part of it (like records and so forth). So if he's being included in the entire process, it might be his way of making that kind of contribution where mom struggles. I mean it's hard to say that you aren't taking an active role... .
when you are.