Well generally with co-owning it's for RL couples or decorators working on houses for another player (See Buttercup, Katt, and Guin). I cannot think of any players aside from Ardin, Link, Maybell and maybe Rocks who has the sheer quantity of stuff to require hoarding across more than 5 homes. I'm an in game hoarder myself so I understand the dilemma but it is worth looking at least removing the block against co-owning at 5 personal houses. Even if it's only for one or two houses (preferably 2 for the boat race game =P) it would make decorators more able to work on multiple projects.