I'm submitting this map for demonstration purposes, in case I never finish it, it shows how to use AI's to launch long-range mortar attacks against players.
I don't know if it will work in multiplayer, but based on the what I know of DFLW limitations, I suspect that it probably will work.
Note: The process is very finicky, and fine-tuning is required to make it work, so if you want a mortar attack in your map, be aware ahead of time that it will require many tests and a lot of trial-and-error.