Are you doing this in a battle map plan or in the battle editor?
No, I am doing this by changing corresponding text file under settlement plans. example: greek_town.txt
I add the farm by copy pasting into city or town text and then adjusting the coordinates.
The last number of the four is the z movement value. Change this to change the height. If you have 3ds max you can also use this and the signiferone export script.
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