GitHub blues - Code Warrior style

I am looking for advice on whats the best way to “harmonize” things using github or a similar tool. I have a rather large project Ive converted to the xojo text based format. I have a release version in both Mac and Win that differ in some typical ways that are both under github sc, where the mac version is the master and the win version is on its own branch. I’ve created a pull request for the Win branch to be merged into the main and it looks great - I can see the differences fairly well in github. Here’s my problem: Im kinda old school. In days gone by (waaaay back) I would use code warrior to merge and set target build directives etc. I really love that “funnel pointing” thing CW had for it and how it let me combine/edit the code while merging. What I would like to do is to edit and add target directives for things like pathing and other unavoidable platform differences as Im bringing the code into the main branch. I have this 2 branch set of code in a good place and Im a tad afraid to pull the trigger and mess it all up. Maybe some of you use github to merge/edit/harmonize this way and have some tips?

For example, I want to “live edit” the win branch files as Im approving the merge: (some edits for brevity & clarity below)

	FullPath = /Users/seana/Documents/GitHub/Tailback/Images/Logo.png
	PartialPath = Images\\Logo.png

	FullPath = C:\\Users\\seana\\OneDrive\\Documents\\GitHub\\Fullback\\Images\\Logo.png
	PartialPath = ..\\Fullback\\Images\\Logo.png

The code above the “----------” is the master branch mac code and the lower is the win branch thats requesting the pull. I want to edit and add the #if TargetWinderz code so I can keep both facets “alive” in the main branch when i merge. So if I just accept the pull request and merge “as-is” I know I will have to go back through and compare the source files to each other and/or find the chokers if I try to run the win branch on mac. That gives me the rot just to think about it. Is anyone else doing this similarly? I like the idea of Arbed but I have the task of convincing non xojo devs to use xojo around the corner so i want to err to the side of common tools here.