Changing user numbers with existing programming

Is it possible to change my user numbers after I have existing programming in the console, without loosing any of it? Or do I have to create new fixtures, and replicate/change type them?

I guess I never had the use for it until now, where I wanted to retain the old programming from some existing fixtures until I found all the hidden cuelists I had with them hidden in. I didn't do a change type (as I'm on 3.1.1) and now I'm ready to delete my old fixtures and want my new fixtures to have the old fixtures user numbers.
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