Or an another solution (maybe)...

In the model there are many objects, each textured separately -> OK
When I combine all the objects/polygons, then the textures are still the same -> OK

But if I would like to create a new UV map to the combined object, the UV editor does not recognizes all the textures, so the UV map is useless in case of combined objects (like in my case)...

Can I somehow create a UV map, where the textures and their position/map remains the same? Because if Yes, what I need only to multiply the texture map with the shadowed one...