Frankensteining - Separate Parts Not Connecting

[Barricade24]

So, I've been doing a lot of Frakensteining lately and I have come across something that I need a bit of help with.

 

I have a few models that I am trying to combine pieces together with, but in certain animations, they don't stay connected.

 

An example of this is I have a model that uses the Stormtrooper chest plate, but has a different back plate. In certain animations, the back piece isn't staying connected to the rest of the chest plate.

 

Anyone know how I can fix this?

[mrwonko]

You'll have to re-weight it to the skeleton.

[Barricade24]

You'll have to re-weight it to the skeleton.

Any particular guides to go about how to do that?

[mrwonko]

Plenty, I imagine, though I can't remember what I used 10 years ago and it wouldn't be quite the same anyway. Maybe start with the Blender manual?