Hey guys, you could do something like this in a script if you're using waypoints;
_heli = _this select 0
_grp = _this select 1
_heli land "get in"
_heli lockwp true
#wait
_helicount = count (crew _heli)
_groupcount = count (units group _grp)
~1
?_helicount != (_groupcount + 2) : goto "wait"
_heli lockwp false
exit