AI orders help

[GR1NCH]

so basically i have Castle like map, i edited AI and everything works fine but, how can i make my AI leave some units in their base at certain region?

i have Towers and i need AI to leave some units there.

 

[IcemanBo]

You can use a unit group variable for your defender units that should stay in base. (DefenderGroup)
When new units gets spawned you can check the number of units in DefenderGroup and decide you want to add it or not.
You can periodicly pick all units in DefenderGroup and let them patrol somewhere in your base or anything you want.
If you don't add a spawned unit to DefenderGroup you logically order it to attack somewhere outside the base.