Well we might have a very different approach from Adri and that she somehow always knew about Haley and MC and more or less adopts her as a sort of daughter and for that reason is willing to share MC with her as long as they are not too obvious. Or something completely different. If remember right from early updates, she kinda liked Haley when they first came over for dinner with her husband and she does not have children. If it would just be a repeat of the Sandra route it would not make so much sense to add that route.
So for me I suspect all three endings will be different. Sandra as the close throuple, Lisa maybe as the more playful but less close one and Adri, well to be honest I am not sure where devs want to take that one.