Changing player's bones without forcing a cosmetic change?

Hi there! First post lol, usually don’t make forum posts but I haven’t been able to find any clear answers on this subject anywhere.

I’ll get straight to the point, I want to modify each default animation that Roblox usually uses by default – specifically just for R6 – but with new/modified bones(joints? idk I’m just calling them bones here. Basically where you rotate/move the limbs from) and/or bone positions WITHOUT forcing the players in the game to change their appearance entirely by just replacing every player’s character with a new model with those bones.

To elaborate, I want to add some new bones/joints(?) to an R6 rig to make it easier on myself in terms of animating, so rather than having to tediously work with one bone per limb to animate complex movement, I have one bone at both the top and bottom of every limb so that I can animate these movements far better without doing the equivalent of trying to lift one end of a long stick off the ground by walking over to the other end and pulling upwards on it until the desired end finally lifts off the ground, with more force than what could have been required given you just picked up the end of the stick you wanted to raise off of the ground in the first place.

I’m already aware that with a rig like this, I can’t just slap an animation I create with my rig with these new bones/bone positions into where the animations usually go and just have it work magically, so I’d like to know this:

Is there any sort of way that I can apply these new/updated bones and bone positions to players in my game, whilst still keeping their usual appearances? If you do have a solution for me, I would like a little bit of a hand-hold-ish guide for any scripting, as I’m still relatively new to Roblox’s programming language/functions specifically (even though I’ve been using Roblox Studio for YEARS at this point. Roblox’s functions and whatnot specifically confuse me for some reason).