Can i copy vertex groups data between object copies that were unlinked?

I have a little composition set up, using copies of same object, but some time ago i have unlinked them. While i know i can link the data, materials and modifiers, i dont know how to link vertex groups data. I need to do that, so i can properly use solidify modifier only to a set of vertex groups in each of those models’ copies (to make them double-sided in Unity).
Only way i know that would work atm is to basically duplicate linked objects again and arrange them one by one again. Which would be a horrible waste of time.
So, is there a way to copy vertex groups data between copies of same object that was unlinked?

I will propably re-copy linked and rearrange them anyway, but i thought i would ask so in future maybe i will be able to save some time with new knowledge.

edit: I have tryied using “transfer mesh data” and “transfer mesh data layout” but it seems not to work for some reason.

edit2: Even with linked objects, whenever i create new vertex group, its not being duplicated on the linked copies. And as soon as i add modifier to one of it, its somehow loses the link alltogether.

Thanks in advance!