The kids who basically lived at your house for sleepovers became family your parents never planned on.

Houses acquire extra kids without anybody signing anything. It starts with a lift home, then a dinner, then a drawer with a spare toothbrush, and at some point your mother is asking after their exam results without being prompted. Nobody decided this. Attendance did it, which is roughly how families form in the first place.

Notice who those people are in your house, and who you are that to elsewhere. Say thank you to the parent who kept feeding you on a Tuesday for three years. And when somebody new keeps turning up, make space rather than treating them as a guest.