Lion,
They will seat the sleeper passengers first and then make a call. But be mindful of the "wonderfully working" (sarcasm) PA system, so after they collect your tickets you might want to head up towards the diner or be close by in the lounge. Keep checking if the train (sleepers) happens to be full as because you're disembarking at ALX it will be necessary that you and your gal can get in shortly after the first call is made.
If I get a chance, I will see who the crew is on #98 tomm down here in FL. They will end up as your crew out of NYP on #91 on the 10th. If I know them (one I used to work with), I'll advise the LSA of what your plans are or at least pass it to the coach attendant. I'll PM you if I am successful with that. Good luck and hope y'all enjoy yourselves.
OBS gone freight...