"High School Family: Kokosei Kazoku" is a gag manga where a young fellow named Kotaro is looking forward to his first day of high school. Until he learns that his father, who never got a formal education, is going to high school with him. And so is his mother, who also had to drop out early. And his genius little sister is skipping several grades to also go to high school. And for some reason Gomez, their cat (exactly how Gomez passed the entrance exam is never addressed, given that in all other ways he's a normal cat.)! They all wind up in the same homeroom as the High School Family.
In Chapter 31, currently available on the Shonen Jump website, one of Kotaro's classmates confesses that he's in love with Kotaro's mother. With a little close questioning, Kotaro realizes that the fellow isn't romantically interested in Mom, but since he was raised by a single father, he's always wanted a mother figure.
So Kotaro gets Mom to roleplay being their classmate's mother, with scenarios going back in time to the classmate being a baby in a stroller (without of course physically regressing.)
This being a relatively gentle comedy, this more or less works out okay.