If you pick a family and change the pv all sprites in that family will have their pv changed.
If you pick an individual sprite, and change its pv the others in that family will stay the same.
Its all about the picking.
Btw you can have multiple families, you can have single sprites belong to multiple families, just like you can have multiple instances of the same object have different pv's, as well as multiple pv's.
Any way post a cap its probably easier to show you than to explain it.
edit:
Yep as well as what quasi said. You can pick with multiple conditions as well.