Hi Cat
Eric and Ernie say, "don't worry about buying any more we'll bring our own!":lol::lol::lol:
Seriuosly though, I had 1 between 2 rabbits and then they both ended sleeping in it, so I bought another and they slept in their own, so then I bought 2 more a litter tray each. They seem to switch between them all.:lol:
You could buy another and see what happens, they may share or take it in turns. I guess it's trial and error. They'll let you know 'm sure.