CreateProcessWithLogon and Marshal.GetActiveObject("PowerPoint.Application")

I have to attach to PowerPoint automation object run from other user. It needs to avoid conflicts with my automation object of PPT and user instance of one.

I created an internal windows user and use CreateProcessWithLogon(...) to start PowerPoint from its logon. Power Point is started normally and its owner is user that I want. But Marshal.GetActiveObject("PowerPoint.Application") returns the error Exception from HRESULT: 0x800401E3 (MK_E_UNAVAILABLE).

I could find the only mention about this method here, but there is no working sample.

Could anybody help me to give an access to PowerPoint automation object run from another user?