For all those who are afraid their food will be "stolen" (i.e. bought up by another realm), I am currently working on a limit flag for trades.
The default is already that people your realm is at war with can not accept your offers. With the new flag, you can also restrict this even more to only allies (excluding those who are neutral or at peace with your realm) or even to only people from your realm.
It won't take long for this to be added.
