Need Help Making Custom Pets

So I know that this has been brought up previously by another user in 2016, but the responses were less than helpful when it came down to understanding the little details needed to truly make my own modification. I understand the basics when it comes to using Asset Manager (making directories, importing files, etc.) but looking at what Crate has already done with their skills and simply altering a few fields in the file on my own gives me less than desired results.

Example:
I want to replace the model for the Summon Hellhound skill, so I go into the summon_hellhound1.dbr and change the spawn config to a Bonerat. Spawning the creature in game with the skill selected summons the Bonerat, but none of the ui elements for the skill appear on my screen (i.e. Health, Energy, or stances displayed in the top right corner). Also I can attack it and I can’t figure out why this is happening, especially considering the fact that I only changed one part of the file. Animations look fine; it attacks, walks, and makes sounds like a Bonerat but it isn’t truly my pet. I believe I have seen other mods without these issues when they introduce custom pets of their own, but the lack of available information for my query is frustrating to deal with.

If anyone can offer some help when it comes to implementing my own custom pets I would greatly appreciate it. I tried messing around with Asset Manager for days and it’s not very easy to troubleshoot when issues like the one mentioned above occur. I don’t intend to make a whole new mastery, just messing around with and altering the already present skills within the currently available vanilla masteries. I saw the tutorial from seven years ago on how to use Asset Manager to make my own mastery (which is what started me on this path initially), but the lack of concrete details for editing .txt files, replacing the icons for the skills I want to alter, and implementing said changes left a lot to be desired.

TLDR: I need help understanding how to implement custom pets, and associated skills in modifications for my own use. I want to be able to use this as a opportunity to learn something I have never done before.

I would also like to create a pet that can go to town and dump off some of your stuff in areas where you cant use your portal.