I bought into that idea for around 20 minutes after finishing Episode 6 since I wasn't all that invested in Jill and only picked her date in the CHICK-playthrough cause I knew imma go with Sage on the DIK one anyway. But reading the things she says during the date makes it very obvious that there is no reason to believe she is your aunt.
Think people are just going with the obvious "MCs mom used to be rich and is dead" and "Jill is rich and had a sister that is dead" and directly connecting the two. The problem with that is that when Jill explains why the tree where you have the picnic is her favorite spot she tells you it's because she used to spend time with her sister there. Her sister would write and Jill would read. Meanwhile the MC constantly points out that he has never seen his mother because she died at childbirth.
If Jill was old enough to read while her sister was still around and we know that after the MCs mom left her home she first lived with someone else and then eventually met Neil, then this theory doesn't really seem valid. For all this to have happened after Jill was able to read she'd have to be at the very least 4-6 years older than the MC but somehow still attending the same college he is. Dawe might be dumb enough to still sit in that college when he's eventually 50, but I don't see Jill being there for that long.
Don't get me wrong, I'm pretty sure there will be some connection between the MC and Jill because just going off of dramaturgy it would make sense to mention how rich and spoiled his mother was before she hooked up with Neil and then tie her to one of the rich prep-families. I just don't think it will be as easy as "she's the MCs aunt".
