as mentioned above but tldr version; be aware though it will take ages to load :D
mklink /J "C:\Steam\steamapps\common\DCSWorld\Mods\terrains\Nevada" "D:\DCS YER YOK\Mods\terrains\Nevada"
mklink /J "C:\Steam\steamapps\common\DCSWorld\Mods\terrains\PersianGulf" "D:\DCS YER YOK\Mods\terrains\PersianGulf"