...I've noticed several times after checking the G*Pall list that there are several jumpseaters on the flight, even if it's a wholly owned airline, don't they still have to introduce themselves and "ask for a seat" even if they were assigned a seat in the cabin? I ask gate agents if there are any listed JS and most of the time the response is no, but we later find out that there were people listed.

what's the procedure for this? can we
deny them boarding for not checking in? I rarely check in with the crew when I'm on a D2 pass on AA, but I'm assuming since we are a separate airline from the other two WO, we still need to check in, right?