This is a brief writeup on how I create PRP previsibine patches.

I use FO4 NG, CK NG, and the latest CKPE for this, with bBSPointerHandleExtremly=true, but you can use older versions. I had bad luck with using the simple downgrader with an older CKPE, so I stick with NG for my CK work. And I use the latest xedit (FO4Edit) from the xedit discord, currently 4.1.5k. Also, I know some people have issues running the following scripts through MO2, but I've always done it that way, and only had one or two issues where it lost focus in xedit and had to resume the bat file.

Get the latest scripts from PJM's Precombine - Previs Patching Scripts, including the main PJMScripts file, all the updated .pas files, and the updated GeneratePrevisibines.bat file. Put all the scripts (the .pas files) in xedit's Edit Scripts folder. 

I put the GeneratePrevisibines.bat in the root of xedit, but you can put it elsewhere, as long as you have it pointed to start in xedit so it can find it.
Now, find a mod you want to make a previsibine patch for. It should either have broken previsibines or won't have them built against PRP. My advice is to start small, to make sure you know how to do this without wasting several hours. The less complicated for your first couple of patches the better.

Open xedit with only the base game files, unofficial fallout 4 patch.esp, ppf.esm, your mod and prp.esp, in that order (if building against vanilla, you wouldn't have ppf.esm and prp.esp, but in that case I'd copy any fixes over from ppf.esm into a patch so you get the bug fixes that you'd miss from not having PRP).

Select the mod you're patching (and any patch files you've created for it as well) and run the script FO4Check_Previsbines. This pops up a dialogue box with several options. I normally use option 4 > "Create Seed to Rebuild Previs in selected Plugin(s) for improve FPS". Then click Okay, and it will run the script, creating a new file called xPrevisPatch. This is a seed that the Generate_Previsibines.bat will use to create the patch. You should review it, and make sure it is covering all the cells you want rebuilt. By default it will include cells in the same cluster of any cell being rebuilt. You can see the clusters Fallout 4 uses in my Previs Cluster Spreadsheet. 

Next, I add masters of all the DLC, UFO4P, PPF and PRP, and then sort masters. There's some debate on if that can introduce new errors, but if you are using PRP, it makes sure your PRP previsibines patch loads after PRP. And I haven't seen any issues in game from doing this.

Finally, you're ready to run the Generate_Previsibines.bat. Again, I have mine set up to run through MO2, and have it pointed to start in the xedit directory, along with the Steam AppID override of 1946160, like you have for Steam CK. It will ask you to name your patch. What it is actually doing here is renaming xPrevisPatch. So give it something like modname_previs_patch. DO NOT USE SPACES in the name. And you can't rename this later, so make sure you name it what you want the patch plugin to be named.

After giving it a name and saying Okay, it should start cycling through Creation Kit and xedit. Do not touch your computer while it is doing this, or you can remove focus from xedit and it won't complete what it needs to do. Eventually, it should finish and generate four files. They will all start with what you named your patch. Any other files in your Overwrite directory can be deleted ... those four files are your previsibine patch. Move them to a new mod, enable it, and test it out in game. You will also want to move the xPrevisPatch seed file someplace else, until after you have tested your patch.

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