There is no requirement to provide 5 sleeping spaces for 4 people.
In the past, most of the wheelchair accessible rooms with roll in showers had one king size bed and the possibility of bringing in a roll in bed. That meant that an accessible room with roll in shower had beds for 2 or 3 people, while a non-accessible room had beds for 4. In that case, they may have given 2 rooms for a party of 4. The reason would be that the party of 4 would have fit in a non-accessible room, but the accessible rooms had only beds for 2 people.
They do not do that anymore because accessible rooms now have beds for 4 in most cases.
Some roll in shower rooms at all resorts have been renovated recently to have either 2 double or 2 queen size beds (depending on the resort).
Those rooms have beds for 4 people, which is all they are required to provide. Who sleeps in which bed is up to you, but the resorts are not required to provide 5 beds for 4 people.
At some resorts, you may be able to get a roll away - the Disney Vacation Club (DVC) resorts do not have/allow roll aways.
As another poster mentioned, you could also bring an Aero or other blow up bed.
Or, you could choose to purchase an extra room - then you would have 4 beds and your daughter could have her own. If you choose that option, request connecting rooms so that you can open the door between the rooms to allow you to move between the rooms without going outside.
If you don't need an accessible room, there are some rooms that have beds for 5. I can think off hand of these:
- POR in the Alligator Bayou area has 2 beds and a small pull down bed.
- Some of the DVC 1 bedrooms have a King bed in the master bedroom, a sleeper sofa and a single bed size sleeper chair in the living room. These include Old Key West, Bay Lake Towers and some DVC villas at Animal Kingdom.
- All Star Resorts and Art of Animation have family Suites that sleep 6 (queen bed, sleeper sofa and pull down bed).
- Some rooms at Contemporary in the Garden Wing sleep 5.
- Fort Wilderness Cabins sleep 6.
- I believe that Swan and Dolphin also have some rooms that sleep 5 (these are on Disney property, but are not owned by Disney).