Master Pose Component with multiple mismatched skeletons?

Hello,

I’m developing a customizable character system, and I’ve been experimenting with Master Poses and Slave Poses. My initial approach was to have one skeleton across all of these, but as I realized I needed jiggle bones and physics driven parts on these individual character pieces (e.g. antenna on a backpack, straps on a jacket). But, I’ve run into problems when setting the master pose component in the blueprint; the joints that aren’t defined in the master skeleton aren’t moving with the character.

This is my character with the backpack with a partial skeleton match, but with the addition of the antenna joints added to it:
Capture.PNG

Now, I wonder if there’s a better approach to having jiggle/spring bones on these individual parts instead of having a huge unwieldy skeleton with all these moving parts, but my searches have failed to find anything…

Does anyone of you guys have another solution to this problem? Cheers!