Selecting Bone Chains / Groups via Animation Rigging UI

So I'm trying to reverse-engineer the UI portion of the BoneRenderer to allow me to both group multiple bones or select and group entire bone chains (by clicking the first, then the last bone in a chain to select it) so I can then group these too into a list and perform some actions on them.

I am struggling to find time to reverse-engineer the entire backend UI of the Animation Rigging package just to allow me to grab the correct bones / gameobjects so I can do something with them. It seems like this is mostly already done, but I can't figure out the right entry point to do the sort of thing I'm after. Honestly, it seems like this click operation would be better suited as an EditorTool than some obscure collection of scripts....

Would anyone be willing to offer some advice on how to approach these two methods of bone selection with this UI? -- It really seems very limiting and painful to modify as-is...

 

Despite this being a particularly handy mechanism to have natively (for all sorts of purposes!), this isn't really what I had in mind.

Specifically, I just wanted to extend the Animation Rigging interface a bit by providing actions that can happen across the selection of bones (up/down a chain, for example) so that constraint components would be easier to add/modify en-masse.

I don't need proper object groups per-se -- I just wanted to make contextual operations in the scene act on a group of bones easier to apply to, for example, a bone chain or selection of bones. Doing this with something like selection parrot would be too much of a hassle initially.

Does this make sense?