Unless menopause carried over along with the grey hair, there's no way those grandkids don't end up with a few aunts and/or uncles younger than they are.
kinda lazy but Chapters 34 and 35 by the weekend probably. I also have volume 1, which includes a 28 page original story about how they became younger (yeah there's more to the lore). I'll probably get to it someday but my schedule's quite tight so probably like end of the month.