We've always arrived at the same time for everone in the same cabin but this time 2 of us are coming from Disney World and 2 from the airport. I am hoping we can check in and board as each pair of us arrive at the terminal. Anyone ever had this problem? 
Just be sure each person has their own ticket and I.D. which they will need to get into the terminal. Who ever checks in first, just expain the rest of the party will be checking in at a later time.