I have a similar system, although my groups are name "MAP x share", where "share" is a share mnemonic, and "x" is the drive letter that I want to map it it. I prefer this becasue it keeps the drive letters consistent.

The following code should work for you:

Code:
Break ON
$=SetOption("Explicit","ON")
 
Dim $sHidden, $sFS1, $sFS2, $sFS3
Dim $iIndex, $sGroup, $sGroupRN
Dim $sDriveList
 
; Define constants
$sHidden="$$"
$sFS1="bar.com"
$sFS2="foo.com"
$sFS3="other.com"
 
$sDriveList="S:I:J:"
 
$iIndex=0 $sGroup=EnumGroup($iIndex)
While Not @ERROR AND $sGroup <> ""
	; Drop domain name.
	$sGroupRN=SubStr($sGroup,InStr($sGroup,"\")+1)
	Select
	Case $sGroupRN="_PTK"
		If MapDrive("N:","\\"+$sFS3+"\"+"PTKSHARE"+$sHidden)
			"ERROR: Cannot map drive 'N:' to path '"+"\\"+$sFS3+"\PKTSHARE"+$sHidden+"'"+@CRLF
			"REASON: ["+@ERROR+"] "+@SERROR+@CRLF
		EndIf
	Case Left($sGroupRN,1)="_"
		; Handle special group mappings.
		If $sDriveList
			If MapDrive(Left($sDriveList,2),"\\"+$sFS2+"\"+SubStr($sGroupRN,2)+$sHidden)
				"ERROR: Cannot map drive '"+Left($sDriveList,2)+"' to path '"+"\\"+$sFS2+"\"+SubStr($sGroupRN,2)+$sHidden+"'"+@CRLF
				"REASON: ["+@ERROR+"] "+@SERROR+@CRLF
			Else
				$sDriveLetter=SubStr($sDriveLetter,3)
			EndIf
		Else
			"ERROR: Exhausted drive letters."+@CRLF
			"       Cannot map share for group "+$sGroup+@CRLF
		EndIf
	Case "Default"
		"No special handling for group "+$sGroup+@CRLF
	EndSelect
	$iIndex=$iIndex+1 $sGroup=EnumGroup($iIndex)
Loop
 
Exit 0
 
Function MapDrive($d,$p)
	Use $d /delete /persistent
	Use $d $p
	$MapDrive=@ERROR
	Exit $MapDrive
EndFunction


This will map _PTK to a hardcoded path (on drive N:).

The first group starting "_" (which is not _PTK) will be mapped to S:, the next to I:, and the third to "J:". Any "_" group after that will issue an error message.

If you want to add more drive letters to the available pool, just change the $sDriveLetters variable.