You can blend them using photoshop, just render out the pfx to .tga images, and then place them in a layer above the MR render.

Also i would desaturate some of the red on that hanging cloth. It looks a bit unnatural against the plain colors in the rest of the scene. Of course the plants may couteract that and make it look fine when they are added. Another reason why adding all the vegitation would really make the scene look alot more alive.

Only other thing is the transpacency mapping you used on the TV Antenna on the roof looks just a bit weird, maybe it needs a slightly higher resolution.

Keep up the great work.