This feature is not available through the graphics driver options available, the only way to do this would be customizing the driver through a Field Application Engineer (FAE).
However in your case due your system has switchable graphics I recommend you contacting the system manufacturer because the Intel graphics driver has been customized according the equipment specifications.
I contacted the system manufacturer and was informed that they cannot help me with this as they only provide standard drivers. I would, however, still like to get this working. Is there any way to get an FAE to customize the driver? Or can I download an SDK of sorts somewhere and give it a shot myself? Depending on the way "Display1_DownScalingSupported" is implemented, it could be as easy as adding some resolutions to a list, couldn't it?
Looking forward to your reply,