Think of the television remote as a flashlight, however the “light” is a flood light, not a spot light.
When ever you light up the infrared light the entire area of you interior, for the most part, is bathed in infrared light.
The televisions “see” this light and respond.
So a simple solution is to blind the offending set just enough so it can not see enough of the distant remotes light to respond.
A piece of tape across the detector on the face of the set will do the trick. In this way the bed room set will still respond to commands with the remote pointed directly at it. The same is true with the galley set and it’s remote.
Look carefully at the front lower edge (depending on model) of the screen and you can faintly see a small rectangle underneath the surface. That’s the infrared detector.
This method works for us. The only problem now it finding something worth watching.