Is it possible to install Windows 8.1 on a disk with two other OS X versions?
WARNING:

If you create another partition in OS X after installing Windows with Bootcamp, it is very likely your Windows partition will become unbootable. Apparently Bootcamp cannot handle more than 4 partitions: EFI, OS X, Recovery, and Bootcamp/Windows.

Be sure to make backups and be aware of the risk of losing your Windows partition if you create an extra partition in OS X after installing Windows with Bootcamp.