I've been doing some homework on this issue. Here's what I've found so far.
I've started using Krita. (Very much a beginner). It has some very powerful tools. But it has 'Transformation Masks'. https://docs.krita.org/Transformation_Masks The short experiments I have done so far makes me think Krita has the ability to do what I'm after. Yes it doesn't 'create' data that's not in the photo but it does allow you to pull and push selections in any direction.
So I'm dropping a big hint here to the PL folks. How about a similar feature in PL. Would save me a lot of back and forth between software.
regards