Exporting a multi-material mesh with GLTFExporter splitting one part per material

Hi all,
I have a model which has few meshes and each mesh has multi materials. when exported the file using using GLTFExporter I can see the multi-material mesh is being split into multiple meshes (clone of the original mesh) at same position and each have single material.

I have found on the forum that the multi-material mesh will be split into one part per material.

But the two issues here are for example

If my mesh has three materials applied to it with color (green, red, blue)
90% of mesh is filled with green material
5% each for red and blue material.

and after conversion GLTFExporter split multi material mesh into multiple meshes say
mesh1 color green
mesh2 color red
mesh3 color blue

Now is it possible for us to create a mesh with same area of material colors applied to it? (multi material mesh using GLTFExporter)

If not can we break mesh into three different mesh each having single color applied to it?

Any help in this topic will be much appreciated.