[FEATURE REQUEST] overlay cropped image onto input image in same location.

[o0oradaro0o]

Is your feature request related to a problem? Please describe.

Frequently after upscaling an image I'll go to gimp, crop a 512 by 512 section of the face or hands or any other part that needs a touch up and use img2img regenerate many variants of that part then go back to gimp and have to meticulously line up the newly generated portion with where the cropped section was.

Describe the solution you'd like

In the "crop" mode I'd like to be able to have a rectangle the size of the selected output width and height from the sliders below and move it onto a section of the input image. when I hit generate I'd like for the outputs not to just be of selected rectangle but of the original input image with just the selected rectangle replaced.
in an absolutely perfect world there would also be an "edge transparency" slider for this mode so that when the new image is overlaid onto the original there aren't hard lines but rather a transparency gradient around the edges.

Describe alternatives you've considered

So far i just do this process manually in gimp but I'm slow at it. I've considered building my own tool to automate the process but it would definitely be smoothest integrated.