Actually this is very possible, you could do it yourself with just a bit understanding of modifying python texts, and copy and pasting. Here is what you do.
But before we get started, I really recommend you download Notepad++
It makes editing the python files a breeze.
Learn how to add companions to the game with this guide here.
http://forums.taleworlds.com/index.php/topic,130815.0.html
Now once you understand this tutorial, you are going to need to get the source python files from both DIPLOMACY 4.1 and DIPLOMACY 3.3.2 + Companions"
Once you have both, you need to copy and paste all the relevant scripts from the companion source files, over into the Diplomacy 4.1 files.
Really though, take a look at that tutorial. Once you've got it down you shouldn't have too much trouble getting everything to work. Just keep in mind that scripts are very pick, and if you add in an extra dash or comma or an unneeded parentheses then the script isn't going to functional correctly. Good luck.