How to change material opacity in a group of a obj file

Hi, I have an obj that has multiple groups inside, after loading in the scene it became a group with multiple meshes as children. But at the same time they share same material.

I would like to affect material properties like opacity individually to each child, but probably because of the fact the material is shared, if I change it in one child it affects to the rest of the objects from the group.

On the other side, if I would manipulate scale or position attributes they behave correctly only affecting to the specific child.

So my question would be if an object with children that shares a material would be able to change opacity of the material only for a child and not for the rest.

Maybe the only approach is to load mutliple textures on for each child and so I can affect them individually. That could be a solution but right now if I could manage that using a single texture would be the best case.

Thanks in advance