In she pops to their common room.
"Hey, you." They have never admitted to having names; Bella picks out particular ones to address, when necessary, by pointing or referring to what they're wearing. "How are things?"
"There's space in the dorm, I'll expand it if you need more," Bella says. "If that isn't the question I'm really confused."
"Wait, hang on - they need my permission because they don't want to go around affecting my minion supply without my say-so, or they need my permission, literally, otherwise no baby minions?"
"How," says Bella, "does that work, exactly, what do I need to do to formally supply permission?"
"Well, that was hardly polite of her. You know, I could probably just magic it so you don't have to go through this rigmarole?"
"I'm not most people, if any of you would prefer stop minioning you can. Is there any reason you want to be minions besides that just being the kind of species you are?"