It really depends on the individual rabbit. I've had rabbits that went from home to home and never batted an eye -- they just weren't phased at all. Some take months to warm up and adjust.
However, it's pretty normal for a rabbit to lose their box training in a new home, even if there aren't other rabbits there. The new owner has to be committed to cleaning up and working on the manners again until the bunny settles in.
We are as gods to the beasts of the fields. We order the time o' their birth and the time o' their death. Between times, we ha' a duty. - Terry Pratchett.
"Men have forgotten this truth", said the fox, "But you must not forget it. You become responsible, forever, for what you have tamed. - Antoine de Saint-Exupéry
