Just finished my first session of this game, and I had a few comments to make.
First, I'll agree with some of the other comments that the daughters canon ages were ones I found quite jarring. I need to stress, that this isn't because of their appearances, for the most part. Though on the note of appearances, I'll say that 18 is the sort of age where you stop growing, heck, even earlier than that in most cases. I was 16 when I reached the same height as my 20~30s adult siblings. I get that you want to use their differences in heights as a way to convey their ages, but at 18/19/20? I'd expect them to all be around the same height honestly.
And yes, girls with that body type do exist, I knew a girl who was below 5 feet in height. She used to joke around about how she was less than an inch too tall to legally classify as a dwarf. The thing is, all of the girls related to the MC seem to have the exact same body type, and the MC himself is a big buff dude from a family who are, well, at last bigger as a general thing. I'd have personally liked a bit of, variance? in their body types, rather than them all being cast from the same mold.
Technically, you can end up with a family consistently like that, though you need to be prepared for it to be the start of what is jarring about it.
Now, ignoring their appearances and personalities entirely, what really bugged me and was the most hard to swallow part about the game regarding their ages, was the sub plotline going on in the background where your sister was telling you / the kids that you weren't going to return.
You straight up said, twice, that the reason behind that, was that she wanted the kids to move in with her / grandma, to be taken care of. This line right here, makes no sense when dealing with young adults like these kids. Heck, family coming over to help is one thing, but having them move in with grandma? That's a conversation to have with them.
Yet the dialogue acts as if these are children without a guardian that need one, and if you aren't around, then BAM, off to family they go with.
It's my biggest issue with the game overall to be honest. I'd suggest going back and removing that bit of dialogue. It doesn't offer anything, it's unrelated to that sister saying mean and hurtful things, and doesn't add anything other than offering confusion because it really sets a tone that your kids are straight up children. I'd have been able to accept their canon ages soooo much easier, were it not for that one thing just bugging me.
Second, I didn't like the jump for Sophie's camera angle. Initially we only got "Top down" perspectives of her that really sold her as short, only to suddenly transition into her standing next to her friend, who we had exclusively 'eye to eye' perspectives of, and the shift was quite jarring.
Third, And this is another comment on their ages. I think you have some dialogue that keeps trying to "Convince" me that the things commenters do / would say means they are children, aren't. That whole conversation about why the girls still stay with their father despite being 18+ was just nonsensical. People do that, heck, I lived with my father until I was nearly 30, just to save money on a house deposit, and I know many people who did the same. The justification for "Why" they still live with him was so random to me, that it just felt like you were trying to justify / convince to me, that they aren't underage. I'd cut back on that.
Lastly, Narratively I like what you have going here, but I've always despised characters that withold important information, and doing so purely to delay the plot or make it work. Here, we have MANY characters refusing to answer direct questions about themselves and others, even though the MC was canonically known to have known and accepted it before hand.
For some of them, I understand why they aren't saying anything. For others, I get why they delayed. A couple? It felt like the ONLY reason they were witholding that information, was to force in another 2-3 days of content before dealing with that information.
It's up to you whether you do it or not, but I just wanted to say that information blackballing is my biggest personal pet peeve, especially when it doesn't seem to make any sense.
On the whole, I did like the story, the narrative and I'm interested to see where the plot goes. These are just some thoughts that, to me? I'd leave as the negatives in a review for a finished product.
Good Luck on your development, and happy gaming to the rest of you.