Exporting a combinedmesh from Maya to UE4 problem

I have a glass window object in maya, which is a combination of 3 different objects (glass, frame and handle) each has its own materials. See picture:

And here is the hypergraph:

When I export it to unreal, I only see one material

But for another object with two material, I see both materials there - using the same export and import settings.

Also when I build the lighting, I get this error:

Lightmap UV are overlapping by x%.
please adjust content - Enable Error
coloring to visualize.

I layout out each individual object UV similar to this UV layout:

but after combining the objects the UV set looks like this:

I assume that’s why it’s giving me that error?

Any help would be greatly appreciated. Thanks.