In an overlap check, you can use system pick nth instance, where instance 0 and instance 1 are the two objects involved in the overlap check.
So logic is on overlap, pick Family nth instance 0 and set a variable to family.UID. Alsp pick Family nth instance 1 and set a variable to family.UID. Then you have the UIDs of the 2 objects involved in the collision, you can send them through a function as parameters to check if they are the correct objects.