Welcome aboard, Latisha! Congratulations on your upcoming sailing with
Disney Cruise Line! I'm thrilled to hear that you were able to book one of the coveted Family Cabanas on
Castaway Cay! Having your own private cabana and beach area is a wonderful way to relax and unwind in a more private setting with excellent perks just for your family!
If you were only able to book three of you, I have a feeling that you must be traveling in more than one stateroom and with guests who have either not sailed with Disney Cruise Line before, or are not at the same Castaway Club level as you are. Since the three different Castaway Club levels get to begin booking extras like the Family Cabanas, earlier than first time guests, and at different times based on club level, it may be that you were only able to book those into your cabana that are eligible for online check-in right now. If you have
first time cruisers sailing with you, they can't begin
online check-in or booking
Port Adventures until 75 days prior to sailing. Since I don't know your specific situation, I recommend you call the agents at Disney Cruise Line at (800) 951-3532 to discuss this. They will be able to view your specific reservation, as well as that of your additional guests to give you more specifics.
You will not be sharing a private cabana with other guests that you don't know, so don't worry about that. But, if my guess is right that your guests just haven't been able to begin online check-in yet, you should be able to add them to your Family Cabana once their online check-in date arrives.
Have fun planning and enjoy that cabana, Latisha!
Marcy