FFMM (++anal or non-anal), with POV and NonPOV Males.
friendly dinner when 1 of each couple FM are planning to have a swap, she sucks him and he masturbate her on the kitchen, while the other 2 are on the dinner room, the female starts getting hot with her partner, he isn't comfortable but he's getting hard, on the other side of the table the other male starts to masturbate his partner, she is also not comf... I left the following to you guys.
I am not a big fan of FFFM, I have tried it myself and it's too many to handle.
if you are short on males, FFM with 2 passionate girls (I really mean it, like the male is only a extra that they forget sometimes, but he is better than a dildo) is the better, but FFMM/FFFMM are always the best as for the POV/Non-POV in the same scene.