[Kayen]

I didn't test this but it should work theory, just put this on the primary mob. You don't need any code on the leashed mob.

#Place code this on the primary mob
#Lets pretend mob that is leashed to this mob is ID 1001.
#Put this on a say 30 sec timer? Even a minute would be ok. This should cause no huge increase in cpu use at all......

if ($timer eq "LeashCheck") {
 $LeashedID = $entity_list->GetMobByNpcTypeID(1001);
 $distanceCHK = $LeashedID->CalculateDistance($x, $y, $z);
#This will calculate the distance between this mob at current location
# and the mob that is leashed to it.
   if ($distanceCHK >= 500) { #Whatever distance you want
   $LeashedID->WipeHateList();
   $LeashedID0->GMMove($x, $y, $z, 1);
   #Clears hate list of leashed mob and warps it back to first mob.
   }
  }