Sorry, I think I misunderstood before. If they are currently using the same name as they used in PT7 (regardless as to whether they changed their name to it), then they should be fine since Paratext matches them up based on their name.
Also, @anon070596 can correct me if I’m wrong, but I’m pretty certain that using their PT7 registration code is just to automatically accept a user to their previous organization. If they have already gone through the effort to re-join their organization, there probably isn’t much point in having them re-register using their old PT7 registration code.