Several materials - To one UV map

I created some models in Maya, UV mapped it, added shaders to different models and then exported it as an fbx.

Then I Opened it in Substance Painter (SP), baked the maps, did some painting etc.

Then I exportet the maps in the format that I need.

Now, here is my problem.

The model has 1 UV map, but for each shader, SP create one material with its own UV map.
It does not just add the materails for one model, on the area on the UV map, where that moel is placed, but instead it fills out the rest of the UV map for each shader.

So I end up having to cut and paste it together in photoshop afterwards, to create one map for one shader, so I can use the ONE shader for the whole 3D model (in this case, a room).

Am I missign some feature in SP? or is there no way to paint several models at once in SP, add diffrent materials to each model etc. and then have it spit it out one combined UV map?

I have attached 2 images, the one is what substance spits out, the other is an exaple of what I would like to end up with.