Just tell the wait staff who's paying for who. They can split the checks. They can split appetizers. I literally do it everytime I eat out with my parents and friends and it's not the end of the world. Plus nobody has to worry about having the right amount of cash. Everybody can use their credit card. It's just easier. If you have to talk about who's paying for who or how much who owes who you are doing it wrong and you're just making it harder on yourselves.