Keep 'em OUT.......
The flight deck is for operating crew and positioning crew when no seat in the cabin is available. Also CAA, FAA, LBA, RLD (etc) types on flight check duty.
Also SHOULD be for ATC types for fam flights, with out question.
It is NOT for, parents, aunts, uncles, cousins....and especially snotty-nosed kids.
Keep the family right and truly....OUT.
IF they want to travel, let 'em buy a ticket, like everyone else.