Need help with general modding

[Mallia]

I'm trying to create a mod to create types of seraphs: thin, normal, and fat. I've already created thin and fat versions of what I want to be affected using the model maker, for example the chain mail armor (see below)

...\assets\survival\shapes\entity\humanoid\seraph\armor\chain\body.json

I used the above file to create the fat and thin versions 

...body_fat.json

...body_thin.json

 

Which I'll have to add to the ..\assets\mod_domain\shapes\entity\... folder

I need help with two things

1. Getting a selector to show up on the character creator. That allows me to choose the seraph's body type (Normal, Fat, Thin)
2. Using the selected value from above to get vintage story to use altered assets when running.

 

Documentation on modding isn't that great and also seems out of date. I believe this can be accomplished with json only, as its essentially an asset swap.