I did have done a few different things....I started out with 2 b&w's and a few months later added a 3rd b&w. I also rearranged my rockwork so their "territories" had to be re-established. Then I was offerd a large pair of the O&W's so again I rearranged the rock work and decided to see what happened.
They each took to different corners of the tank until they all established their "place" in the tank. So I ended up having the 3 b&w's and 2 o&w's together in a 75gal for years. I loved it.
Right now I have 3 baby B&W's, 2 large O&W's and a true perc in the 75g but I do have the divider until the babies are bigger.
Good luck if u decide to try....just make sure u have a plan if things dont go well.