Parkerizing question

Hi, Tim. I have a parkerizing question and thought that you would be the person to ask. I am wanting to know if there is a way to do spot parkerizing on a firearm that has an older manganese oxide finish and is being welded together with Tartan G TIG rod that is supposed to take bluing/parkerizing the same as the surrounding metal beside the welds?

Not Tim but in the past Tim has parked an op rod for me that had a small patch of pitting. I removed the pitting and Tim media blasted the spot where the pitting was and then parked the op rod. I wanted to maintain as much of the original finish and it came out pretty good.