Hi Kathy,
if you have a decent lease it shouldn't matter if there are 4 members of the same family, or 4 unrelated people.
Everyone's name goes on the lease.
They all get credit and history checked.
They are all responsible (jointly) for the deposit and the rent. It's not your business to work with them on splitting the rent or the deposit.
If one guy is tardy with his portion of the rent, that's not your problem. If the rent is not paid in full to you by the agreed date, they are all under notice to Pay or Quit.