How do I rig the transparent part at the back to the torso so that I can animate the transparent part? I made the transparent part the humanoid root part, anchored it and joined it to the torso using a plug-in but when I try to animate the part, the torso moves instead. I was able to do it once successfully but after I resized the part, it stopped working since.
This is easy, what you need is this plugin (I use it all the time on custom characters) Rig Editor - Roblox, best of luck!
There’s a plugin called “Rig Editor”
Try that.
I used the rig editor plug-in, it’s easy to navigate.
We both replied with the same thing, at the same time 
Haha, funny. I guess we both use the same stuff.
Yeah i’m using that exact same one and it worked once but now IT’S NOT WORKING, WHY DID I CHANGE IT BACK ARGHHHHHHHHH
Use the Plug-In Rid Editor and make a joint from HumanoidRootPart > Torso
Make sure the HumanoidRootPart is the PrimaryPart of the dummy and make sure its anchored, hope this helps!
Are you referring to the same plug-in as linked above?
Try to anchor it like Cixda said.
If anchoring doesn’t work, make sure that the parenting is proper, same with the welds. If this doesn’t work, I tried
What do you mean by this? Make sure I click the hrp first then the torso or what?
Welding it to a specific part usually works for me i’m not sure if it would work in this situation.
First, get your character
Get your transparent part
Make sure “Join Surfaces” is off
Drag the part onto the back of your character
Now, put that part into your model
Open the Rig Editor and select your rig
Click the torso and the back part
Now, make sure to set the joint part0 in the backpart to torso, not humanoidrootpart
Rename the joint to something memorizable, like “Backpack” or something like that
You are free to animate!
Remember that if you weld anything to this back part, the welded parts will move along with it!
What I mean is that when you weld, you should click the base part first, then the part you want to weld to it.
According to your image, must I create the joints throughout the whole body as opposed to just joining the transparent piece and the torso like i’ve been doing? If so, do i join both arms and legs, and head to the torso?
Nope. I thought you were using the premade R6 rig.
saw ur reply indeed funny we did react the same. 