...they literally left it with the perfect segue, Mom and Aunt suggesting that Son goes off to college, finds some cute young thing, and brings her back for them to play with. So part 2 is just that, technically BGGG, but in the style of the first, break it up, have different BG / BGG interactions first with NewGirl, then with mom/ aunt, then NewGirl with Mom and Aunty (initiation time), then you all fall into bed together for the last act, or something along those lines.
The script for MR is one of its strong points. The interaction between Mom and Aunt are beguiling. i dunno how much of that is good direction, ad-lib, genuine chemistry, or what, but it's the magic that animates the scene, and makes it one of the best VR scenes ever shot (in the west).
Final point, i watched this again the other week, watched in many times now, and i was stuck by just how much OnTheTelly blatantly ripped off JAV. Note, this is a good thing! The long-drawn-out seductive, suggestive talking scenes, the constant switching of locations, the interplay between the actresses, the numerous different well constructed sex acts. It has structure, each scene leads naturally to the next, which serves to heighten the final, incredible all in bed together finale. From a directorial view point it's JAV, pure and simple, but translated into western porn style. Sheer brilliance.
So aye, if you can get a director who can replicate JAV, you're half way there...