Can I apply a BP on top of a PSU? Or vice versa? PART 2

I thought I won’t blog about this again: Can I apply a BP on top of a PSU? Or vice versa? But then a colleague of mine raised this simple question: “I have a customer that would like to change from patching using PSU to patching using Bundle Patch. I am wondering what happens if my home has had several PSUs installed. Before applying a BP, would I need to rollback one by one all the PSUs that have been installed in reverse order (tedious) OR only the latest PSU (good)?” Unfortunately the “simple” solution is hidden deep down in…