Yeah, it's not in the game yet, but once we return to Mistral Village into episode 4, the harem system will be introduced, along with the ability to build deeper relationships with the select cast.
The way I think I'm going to do it now is I'll let the player build a nursery to 'turn on' pregnancy events. This'll enable characters to get a preggo belly, which'll alter their sex scene, or even give them a new one. This is one of the reasons I've already added a day counter into the game's system.
I've already prepared pregnant character art for Isadora, Hides-in-Barrels and even Chloe.
In regards to the kids? We'll throw 'em in the nursery and not worry about them.
Also, to answer your other question, I suppose it'd be customary to have at least one of them in for the referential fun of it. If I'm really cheeky, I won't even have to redraw their character art and sex scene