At this point will MC be his own dad, Grandfather and maybe also be his best friend's dad
No, I'm pretty sure ICCreations made it clear during the first updates that MC will not be his own dad, to me it's clear Julia (mom) was already pregnant in the past (she was crying), the dad is probably the asshole bully, also... isn't Chloe younger than him and Natalie? that's proof that Julie was already pregnant.
To be his own grandfather, he has to travel even further in the past and that already happened in The Artifact, I doubt he will reuse that plot... also, tbh I prefer milf and gilf grandma, no reason to have her young version there too.
Now, about being Kim father, that makes a lot more sense, I can totally see MC impregnating Silvia in the past... you know, a long time ago I had a crazy theory about Silvia and Kim, about them being the same person, that theory died when I saw young Silvia but every time I see them talking about Kim getting an haircut I wonder how would she looks if she had her mom haircut and a mature milf body, I wonder if MC will ever travel to the future.