I believe you can set the Sonys to use any of three, discrete code-sets. On the Megachangers, they are termed CD1, CD2 and CD3. Sometimes, the "switch" to tell the device which set to use is on the back panel, sometimes it is accessible through the button menus on the front.
On the remote, look for a little switch on either the top of the remote that has those codes, or look in the battery compartment.
Having a different set of codes for each device should allow you to control them independently and keep them in the same room if you want.
I've not had any success finding CD2 or CD3 code-sets for the MX-700. BUT you should be able to "learn" the different ones.
This issue is ongoing for me, so if anybody else has wisdom or experience, please share.
