Thanks for the reply Richard. I had a feeling that the autoedging was handled in the engine code, it's a shame there aren't any modding options for this built in to allow defining new configurations. Turning off autoedging when placing these tiles seems to be the way to go, however you have to also ...

I was looking at creating some new overlay tiles but keep running into an issue where they do not autoedge to neighbouring tiles of the same type. As an example: NorthernEurope_Overlay/Tiles.txt has Tile 8 which is a road with a track coming off one side. When placed this auto edges to any neighbour...