This is mentioned in the other thread. I'm getting confused with you asking the same thing in two different threads and expecting different answers.

OBJ files are expected to be created with a corresponding MTL file. That's the standard as set by Wavefront when it developed the format for it's own use before it became a standard format used by others including Poser. If Poser encounters an OBJ file without a corresponding MTL file it will create one. No it does not ask you anything. That is not a problem or a fault of Poser. It is the standard for wavefront objects. Some software implements their version of the standard by not importing the MTL at the time the OBJ is but, again; this is not a feature of some software. It is an incomplete implementation for simplicity sake.

As mentioned above you need to take your OBJ into modeling software to fix the multi mats.

You seem to have the wrong idea about the OBJ/MTL file formats in regard to lighting. Illumination maps will not give any illumination. They do not define where an area of a mesh casts more light than another. They define where the mesh does not illuminate 100%. Like a transmap. for brightness levels on parts of a mesh. OBJ files denote 3D geometry only and as such the corresponding MTL file represents the light reflecting properties of that geometry. Light reflecting. That's it. No light emitting. That's why illumination maps don't define light intensity no matter what numbers you play with.