How to freeze part of a frame?

Hi forum,
So during an interview shoot, one of our lights started flickering, fortunately only affecting the background of a shot, and out of the area where the actress is talking and moving around. So, I can fix it by replacing that part of the frame with video from earlier in the shoot.

How do I do this in Resolve? I have the "good section" copied onto a new track above the main interview, but I don't know how to mask it. I can add windows etc, but those only affect that node; what I want to do is "cut a hole" in the entire track and let the actress on the track below show through.

what I want to do is "cut a hole" in the entire track and let the actress on the track below show through.

Add an alpha output to the "atop" element node tree that is defined by whatever qualification you created - window, vignette, combination thereof... Its just a right-click away.

jPo, CSI

There might need to be some slight stabilization/tracking needed as well. It's really amazing how small vibrations and movements even from a tripod shot become visible in a scenario like this.

some slight stabilization/tracking needed as well.

And then you will have to blow them both up to avoid dog-earing the edges. Or grab the freeze after you do the mo-stab.

As Murphy's Corollary states: There are no perfect solutions; only ones that are more subtly wrong.

jPo, CSI