Ok. I did some very basic testing on this here, but it should definitely be tested a lot more. It makes use of fnLDAPQuery() from Chris S.

It's also kind of sloppy, i didn't dim any of my vars or do a lot of error checking, so you should probably tweak it to make more robust.

Let me know if you have any questions/problems.

Code:

break on 
$ = setoption('wrapateol','on')

; get the defautl naming context
; open the source file for reading
; loop through the file
$sADsPath = "LDAP://"+GetObject("LDAP://rootDSE").Get("defaultNamingContext") 
$ = open(1,'c:\Groups.txt')

$curLine = trim(readline(1))
while @error = 0
   ; split the line to grab the new and old group
   $curGroup = split($curLine,';')[0]
   $newGroup = split($curLine,';')[1]

   ; using the fnLDAPQuery function, try to get the 
   ; adsPath of the new group
   $strFilter = "(&(objectClass=group)(Name=" + $newGroup + "))" 
   $aAttributes ="adsPath"
   $grpAdsPath = ""
   $aResults = fnLDAPQuery($aAttributes,$sADsPath,$strFilter) 
   For Each $Result in $aResults 
       $grpAdsPath = $Result
   Next 

   ; If the group does not exist (adsPath not found), then create it
   if not $grpAdsPath
      ;get the adsPath of the current Group
      $strFilter = "(&(objectClass=group)(Name=" + $curGroup + "))" 
      $aResults = fnLDAPQuery($aAttributes,$sADsPath,$strFilter) 
      For Each $Result in $aResults 
          $grpAdsPath = $Result
      Next 
      
      ; from the adsPath of the current group
      ; get the adsPath of its container
      $grpOU= 'LDAP://' +  substr($grpAdsPath,instr($grpAdsPath,',') + 1)
      
      ; create new group by getting the OU object and using the create method
      ; pass it the name of the new group
      ; (creates a global security group by default i think)
      $objNewGroup = getobject($grpOU).Create("group", "cn=" + $newGroup)
      $objNewGroup.SetInfo()
   else
      ; if the group already exists, get that group object
      $objNewGroup = getobject($grpAdsPath)
   endif

   ; using the fnLDAPQuery function, get the members of the current group
   ; Add those memebers to the new group (using the object from above)
   $strFilter = "(&(objectClass=group)(Name=" + $curGroup + "))" 
   $aAttributes ="member"
   $aResults = fnLDAPQuery($aAttributes,$sADsPath,$strFilter) 
   for each $aRes in $aResults
      for each $res in $aRes
         $objNewGroup.Add('LDAP://' + $res)
         get $some
      next
   next
   $curLine = trim(readline(1))
loop

Function fnLDAPQuery($What,$From,Optional $Filter,Optional $OrderBy,Optional $Scope,Optional $User,Optional $Pswd)
Dim $oCon,$oCMD,$oRS,$sQ,$sF,$sGV,$R,$vP,$aR[0],$nul

If $Scope <> "base" AND $Scope <> "onelevel" AND $Scope <> "subtree" $Scope = "subtree" EndIf

$sQ = "<"+$From+">;"+$Filter+";"+Iif(VarType($What)>8192,Join($What,','),$What)+";"+$Scope

If VarType($What)>8192
For Each $sF in $What $sGV=$sGV+'$'+'oRS.Fields("'+$sF+'").Value,' Next
$sGV=Substr($sGV,1,Len($sGV)-1)
Else
$sGV='$'+'oRS.Fields("'+$What+'").Value'
EndIf

$oCon=CreateObject("ADODB.Connection")
$oCon.Provider = "ADsDSOObject"
$oCon.Properties("Encrypt Password").Value=1
$oCon.Properties("ADSI Flag").Value=1
If $User AND $Pswd
$oCon.Properties("User ID").Value=$User
$oCon.Properties("Password").Value=$Pswd
EndIf
$oCon.Open("Active Directory Provider")

$oCMD=CreateObject("ADODB.Command")
$oCMD.ActiveConnection=$oCon
$oCMD.CommandText=$sQ
$oCMD.Properties("Page Size").Value=1000
$oCMD.Properties("Timeout").Value=30
$oCMD.Properties("Cache Results").Value=0

If $OrderBy="distinguishedName"
$oRS = CreateObject("ADODB.Recordset")
$oRS.CursorLocation=3
$oRS.Sort=$OrderBy
$oRS.Open($sQ,$oCon,0,1,1)
Else
If $OrderBy
$oCMD.Properties("Sort On").Value=$OrderBy
EndIf
$oRS = $oCMD.Execute
EndIf
If @ERROR Exit @ERROR EndIf
If $oRS.BOF AND $oRS.EOF Exit @ERROR EndIf

Do 
$nul=Execute('$'+'vP='+$sGV)
$aR[$R]=$vP
$oRS.MoveNext
$R=$R+1
ReDim Preserve $aR[$R]
Until $oRS.EOF
ReDim Preserve $aR[$R-1]
$fnLDAPQuery=$aR
EndFunction