One card per person per entry, even if you have remaining quotas in the same card, you cannot use it for another person at the same time.

The most I tried so far was 4 pax in KLIA1 and no issue.

Make sure all from different banks. E.g. you cannot use multiple MBB or UOB cards.

Not sure for RHB or AEON because I don't have AEON and don't use RHB for lounges. I know the staff will ask you to give other cards. I gave MBB MUVI and Merc Card and they asked me for other banks cards, luckily I had others with me.

I think only one entry per account, regardless of the number of eligible cards you have from the same bank. You can try your luck or these banks are OK, I'm not sure. Best is have different banks. Or you can grab food from Flight Club Grab n Go since each card gives 2 take aways, you can have four and share with your guests outside. I never tried this take away from Flight Club too but there are many people shared on this thread before.

Edit: Oops. Grab n Go only in KLIA2. KLIA1 is normal Flight Club I guess.

KLIA T2, FLIGHT CLUB
take away
each credit card allowed for 2 sets.

i redeemed 2 cards.

there is dine in area there. counter staff will ask dine in or take away, usually take away & go home eat after arrive klia t2

Yes, the staff will ask for different banks. So you managed to get two more cards in time, since you mentioned earlier you only had three different banks.

can share the card you use?

PPL Policy - can i use two cards from the same bank to admit 2 peoples?