If they call the parents, they will just hide the evidence so their kids won't get in trouble!
This search was not invasive in any way. Have a female family member untuck their shirt and lift the bottom edge of their bra away from their body with their thumbs. Unless they have some serious problems, no body parts will be visible to anyone watching, but anything hidden in the bra will fall to the floor.
I agree that a female staff member or police officer should have been present during the search, just to protect the males from unjust accusations.
More information about formatting options