(Need help) Skinning an assymetrical character with assymetrical Blend Shapes & Textures

Hello.

I’m working on an assymetrical model (which I can’t share images with you, I hope you’ll understand) which already has shape keys and textures applied.

I’m trying to figure out a way to work on the skinning of the left part of the character, then to symmetrize the skinning for the right part (my model is assymetrical only on the chest).

I tried several technics (including paying for an addon “Weight Paint Tools” which is not working neither), I can’t find any way to symmetrize the skinning.

The only technics I know is to duplicate the Vertex Groups, rename them from ***.L to ***.R and to mirror them one by one, but I have dozens of vertex groups to mirror. If I have to edit again the skin, I won’t copy, rename and mirror dozens of vertex groups one by one at each change.

Do you know if there is a way to transfer the skin weight of the left part to the skin weight of the right part correctly and professionally, please?

I thank you by advance for any help.