It probably won't happen. Scripts won't affect the map editor, and since placing a tile deletes the previous tiles of the same layer, there is no way to recall what you want to be there from Tile D. The only way I could think of is you'd have to specify it in the script editor using a table to set another layer or something. It would work, but the problem is that you won't be able to see what is being drawn where. The only other way I can think of making a script setup is to have the user put everything they want on TileD/E to another map and then merging the two maps. Either way, it wouldn't be ideal.