How to edit a Rigged 3D Model without Ruining the Rig?

Question

I have some rigged 3D models that I want to use. They came as .fbx. and sometimes I want to make some minor edits such as merging/moving/removing some vertices or something of that nature.

The Problem: That (using Unity & Blender) I cannot seem to be able to make changes to a 3D model without ruining the model's Rig.

Blender's importing seems to be the problem, if you care to take a look - but it may be unfixable.

(The first picture is what happens because Blender f*#ks up the the leaf nodes, the 2nd is me trying to reattach the mesh to a Rig)

I have been completely stuck for a full day; however, it would seem that there are several potential fixes/work-arounds for this problem. And I am wondering which of these you would take? These could be:

1. Figuring out why importing a .fbx into Blender breaks the model. I'm not confident that this is going to happen, so let's discuss other possibilities.
2. Using Unity / Unity's API, and an unedited copy of the model that is working, apply the changes that I've made to the model, and then (instead of using Blender's broken Rig) somehow apply the Rig of this working model to my edited model, such that the same vertices are attached to the same bones, and new ones are attached to the nearest bone, ect.
3. Just completely give up on the old Rig and re-rig it in Blender.
4. Through Unity, somehow applying the vertex changes I've made to the model to the model that does have a working Rig.
5. Something else that I haven't thought of.

This is frustrating and I want to move on to the next thing already, so if Blender's importing can be fixed I am interested in looking into one of the above work-arounds. What would you advise that I look into?

Answer 1

Given that we do not know from what tool did the fbx come from I will just share our experience. Importing rigs from fbx in blender that were made in other tools does not work. Altough blender might have the same functionality as lets say Maya, its internals are different and there seems to be no corelation between features. I would reccomend you give up on your existing rig and re-rig in blender. In the long term this will svae you time by not having to fight ghosts.