To understand this, would be to understand how the device tree structure works.
If you place a device, as controlled by the UIRT, then any messages going to that device, will be handled by the UIRT.
However, if you place the device as controlled by another media director's UIRT, then when the On or Off commands go to a particular media director, then they will also go to the UIRT's child devices, producing some unusual results when you put the room to sleep, etc. (the device in the other room will also turn off.)
In short, you're being a cheapskate. Stop it. You're making things much harder on yourself than you ever should. Save yourself some pain, get the additional UIRT, and set things up cleanly.