Jan, this is an interesting problem. What I do to preserve a playlist is to back it up on my computer's hard drive immediately after I play the gig by sending it to my computer as an email attachment. In that way, if I delete a version of a song in a particular playlist from my iPad, I have a copy of it on my computer. I often have various versions of the same tune, usually for different singers, and like you, I always add a note in the title with the singer's name. When I do a clean-up, I know I can always find a copy on my computer. Of course, this means that I have lots of iReal Pro files on my hard drive. However, each playlist takes up very little space, and storage capacity on hard drives is really inexpensive, compared to the bother of losing a valuable copy of a particular iRP arrangement.