How can I add an additional attachment to the starter characters rig?

Hello, I have very basic knowledge in these things so Ill try to explain the best I can.

I am trying to change the starter characters rig which will keep the original players avatar and r15 body but it will add a bodyattachment which contains a sword and sheath to the rig. I want this attachment to be able to be animated so I can replace the default character animations with the new ones that include the character holding this sword. Simply I just want the player the load into the game with their normal clothes and hats but they also have this attachment to their rig.

I have 2 solutions for this but I’m not sure how to do these:

  • I can get the original starter character and add the body attachment to it so that it can be animated
  • I could get a normal dummy with the new rig and give it the normal players avatar which has the clothes and accessories

I hope you understood this but if not please ask. If you do know how to achieve this then please tell me how and I will try to do this. Thank you.