grievous5226,
You could go into troops.txt and change their names (or just use the troop editor). It wouldn't be savegame compatible, though. Can you edit the names with edit mode on? I've honestly never tried, I know you can edit faces that way.
Tamerlan,
Quite possible, yes. You would just have to make a menu with the appropriate function. You could probably reuse the request to talk with someone menu and just change it to get the guild master slot of that city instead of lords in the castle.
amade,
Sure. Just go into scripts.txt and find
center_get_food_store_limit -1
10 21 1 1224979098644774912 2133 2 1224979098644774913 0 4 0 541 3 1224979098644774912 0 3 2133 2 1224979098644774913 50000 5 0 541 3 1224979098644774912 0 2 2133 2 1224979098644774913 1500 3 0 2133 2 72057594037927936 1224979098644774913
The
50000 is the limit on cities (they consume 500 a day, so that's 100 days worth) and the
1500 is the limit on castles (they consume 50 a day, so that's 30 days worth).
G36E,
Whoops! Sorry about that, I forgot to add it. I'll add it now.
Oldasdirt,
Technically, if you're holding the claimant hostage and ruling in his stead, wouldn't he get mad at you?

It makes sense to me! But if you want to drop the negative relations you can easily do it altogether. Go into conversation.txt and search for
2107 2 1224979098644774919 -1
This is where it turns the relation hit to a negative, just change
-1 to 0 to simply negate the relation hit.