I want to rework how children are handled by the game as well.
Currently, children are stored in the girls section of their mother so if she dies, all her under age children also die.
I want to make something like a children's home for your girl's children and also the possibility of getting new girls/boys from there.
How much you spend on this would influence how much the children learn and how they grow up.
Adding children to free time should be added so if a mother has free time she will most likely spend it with her children.
The more time she spends with them, the better they turn out.
If the children's home becomes a buyable building, then it would include the school so you could assign teachers and have girls take classes.
An orphanage kind of building? With daycare/babysitting jobs for girls to train their maternal skills as well?
Also, consider this as an option to solve the issue of player character immortality - an option for your male sons (or daughters too?) to inherit your empire when the "current you" gets old or dies and become a new player character themselves. A sort of dynasty system where you appoint your heirs. They would start from scratch or some low point of experience and level your businesses, items, buildings, girls etc. would stay the same. Thing of it like something of a New Game+ option.
Not that hard to implement I'd believe - adding a method to rename yourself and wipe all of the stats data, age included, to a clean,new slate should provide a sufficient illusion of a new character taking over.
Should still be optional IMO, I mean the PC could belong to some kind of inhuman race with ridiculously long lifespans if it's so desired.
Also, friendly reminder to check out my other 4 gang mission suggestions in my first reply in case you haven't (only saying this because the former 4 all got into your checklist of potential implemented missions and also to say something on-topic with the thread purpose).