Add a new Dynamic Query to existing group

Hi,

I need to add a dynamic Query to 1000 groups which were created using Powershell. I have the scripts that were used to create the groups, but i cant work out how update a group or add a query to an existing group.

This is the script that was used to create the groups

$members = @(

    @{ Name = "PD9_Query"; Definition = "filter:/Orion.Nodes[CustomProperties.Service_Location='PD9']" })

$groupId = (Invoke-SwisVerb $swis "Orion.Container" "UpdateContainer" @(

        "PD9_Routers","Core",60,2,"Created by the GS© PowerShell script","true",   

    ([xml]@(

       "<ArrayOfMemberDefinitionInfo xmlns='http://schemas.solarwinds.com/2008/Orion'>",

       [string]($members |% {

         "<MemberDefinitionInfo><Name>$($_.Name)</Name><Definition>$($_.Definition)</Definition></MemberDefinitionInfo>"

         }

       ),

       "</ArrayOfMemberDefinitionInfo>"

    )).DocumentElement

  )).InnerText

Could anyone advise on what changes i need to make to just update the existing groups?

Thanks