Is there a tutorial on how to edit someone else's mod.

I have opened the mod in s3pe, extracted the S3SA file. Opened that s3sa in ILSpy then converted it to an IL file with the control panel and opened the file in notepad, edited it and converted it back to dll. Replaced the old s3sa and started the game to see if it was working. But, is there an easier way to do this? I wanted to make the mod base game compatible and I was successful enough, but it took a long time so I didn't finish.

I also want to know if there is a tutorial on how to make the townie's do thing like in the weddings for inactive mod, you can have a wedding without adding the townie to your family or in the just sit mod, you can make a townie sit without them being your active family. I tried to download the social clubs mod and ultimate careers, but that didn't work and my sim grandson got fired even though he had a good trait and he never gave any sermons during church even though my active family could do it in my test game.

The mod I want to change is the olomaya peteran religion give fiery sermon interaction so townies can be made to do it. I haven't updated it yet. I have visual studio installed and battery script utility.