That is: You want to rename all its subpages too?

Oh, that might be tricky. Very easy to do, but it might be very confusing.

The thing is that I don't want to remove the old pages totally. If someone goes to http://www.musmakers.com/67.pagename1.pagename2.pagename3.something4 that page should be marked obsolete and have a link to http://www.musmakers.com/67.pagename3.something4

I'll put it on the todo-list. Right now you need to do it manually by creating the new page, probably re-upload the file (?!?), edit the old page and mark it as obsolete. And do this with all its subpages. I can see why this sucks big time.