Basically- did you want to do the more guranteed way or simply just try? For the guranteed way, you'd be a bit more limited but you'd still get a chance to explore no matter what. We'd also all have to be in the same room when we sleep for it to be guranteed for all of us to get in. The other way is just the normal way but there isn't any absolute proof that'll tell us that it would be successful for anyone to get in.

Description: Apparently, there's a whole room in Yume 2kki where Urotsuki wears the outfits of a bunch of other Yume Nikki fangame characters like Sabitsuki. Take that information as you will :) -Sal