The above is right--there must be one Florida resident booked in each room, and FL resident ID will have to be shown when checking in. No, you cannot book additional cabins for friends/family.
You could work things the same way people sometimes do with teens--you can book For teens, you book one parent in each cabin, fully knowing that in reality, the kids will sleep in one cabin and the parents in the other. If the Smith family are Fl. residents, you could book Mr. Smith and Mr. Jones in one cabin, Mrs. Smith and Mrs. Jones in another.....who sleeps where is your business.