You can accomplish this with Keyclone, but the mouse broadcasting is not a strength of the program.
To do it, you would:

Click Set Up.
General Tab.
Set a "pass-mouse-click hotkey"
And check one-click then off.

Hit the keybind for the ground target AoE.
Press your hotkey.
Click the ground where you want it.

Unfortunately, it will kind of flicker from one screen to another.
Actually doing brief PiP swaps to click everywhere.

With KC, its just as easy to physically move your mouse into each window.



Hot Key Net has a strong mouse broadcast option, and its a free program.
IS Boxer also handles mouse broadcasting very well.

If mouse broadcasting and general flexibility within your program is important.
Take a hard look at these options.