his other game had a harem ending, though not all the permutations of threesome were given real scenes. I think you can get them all pregnant.
So i would expect there to be some sort of harem ending, how satisfying it is from a sex scene perspective remains to be seen.
You can go to work on all girls concurrently, surely there will be a scene where they come together(and then cum together

).
No way he's gonna go, "you should've focussed on one girl and ignored all others" now, it would be the ultimate asshole dev dick move.
Now that we fucked
all 3 of the main ones(plus the aunt) things should move towards bringing them together instead of solo scenes.
Let's see how creative he gets... a scene where you get caught balls deep in one of the sisters could be fun.