YES! This would be a perfect addition. In Sims 3 I had a gay couple that adopted all their kids and fostered a few others. The fostering was unofficial of course as I just added them into the household manually; a kid and at least 2 teens into the household. All in all it was 3 adopted children and if my memory serves me right, they fostered 4 kids over their lifetime. The last one became a YA just before they died.
I'd love to have this as an official option in the game where homeless teens can be fostered. I have at least 2 homeless game generated households that has only 1 teen each. I did have a third one whom I actually merge into another homeless household that contained one adult woman. Being able to have Sims foster kids from other households would be great. For instance, via the telephone or even by requesting a Sim in person to foster their kids for good or at a set amount of time.
I have recreated my Sims 3 gay couple in Sims 4. Well sorta. They don't have the same name, look, traits or the same ethnicity even but I like them anyway :smiley: They have already adopted a child and a toddler and will adopt again, either another toddler or a baby or even both. When the youngest grows up to a child their fostering will start and I think I will start with the homeless teens my game has generated.
But anyway. Yeah, fostering would be cool.