ordering a unit from another group

[hogmason 2]

hi i am spawning pows via script and creating them in a group named _POWgrp

which is fine but when i rescue them they join my group therefore leave _POWgrp

wich then tells my script that they are dead as i am using this code to fail task if to many die.

      if (count units _POWgrp <3) then 
	   {

	    hint "Too many POWs died!";
        ["Task1","failed"] call SHK_Taskmaster_upd;
        [] call SHK_addTask;
	   _POWs_death_Limit = true;

          };

so my question is how can i make them follow my orders but not leave the _POWrgp  group.

this is the rescue code.
[code]
_per = _this select 0;  // Person who had the addAction
_ldr = _this select 1;  // Person who used the addAction
_act = _this select 2;  // ID of the addAction

// Remove the rescue option
_per removeAction _act;

// Join the POW to rescue group. 
[_per] joinSilent group _ldr;

_per EnableAI "MOVE";

[/code]