That may require the HDMI to go into the receiver so in that case you may need to get an external matrix switch. This one I have and it allows 4 inputs and two outputs:
4X2 True Matrix HDMI 1.3a Powered Switch w/ Remote Controller (Rev. 3.0)
about $57.00. Use one output for the TV and the other for the Onkyo.
That website has others as well, search for HDMI matrix switches.
Another less costly solution may be to run the Directv directly to the TV and use optical for the audio. Then run the Blu-ray through the Onkyo since it would only be the loss-less source anyway. That assumes the wife only wants to watch TV without the surround and not the Blu-ray.