Powershell Adding users within groups to cross forest groups - powershell

Question

This script works without error now, but the problem is that when several groups in the searchbase are found, the script will add all users from all groups to the cross forest target groups.
So for example:
ForestAGroup1 = contains 2 users
ForestAGroup2 = contains 2 users
::runs script::
now...
ForestBGroup1 = contains 4 users
ForestBGroup2 = contains 4 users
The ForestBGroup1/2 needs to contain the same identical users as ForestAGroup1/2.
Here is the script for reference:
$creds = Get-Credential
$Groups = Get-ADGroup -Properties * -Filter * -SearchBase "OU=TEST,OU=Shop Print Groups,OU=User,OU=domain Groups,DC=domainA,DC=com" | export-csv c:\temp\test.csv
$Groups = Get-ADGroup -Properties * -Filter * -SearchBase "OU=TEST,OU=Shop Print Groups,OU=User,OU=domain Groups,DC=domainA,DC=com"
Foreach($G In $Groups)
{
#Display group members and group name
Write-Host $G.Name
Write-Host "-------------"
$G.Members
#Add members to domainB group
$domainGMembers = import-csv C:\temp\test.csv | ForEach-Object -Process {Get-ADGroupMember -Identity $_.CN} | Select-Object samaccountname | export-csv c:\temp\gmembers.csv
$domainDNUser = import-csv C:\temp\gmembers.csv | ForEach-Object -Process {Get-ADUser $_.samaccountname -Server "domainA.com" -properties:Distinguishedname}
import-csv C:\temp\gmembers.csv | ForEach-Object -Process {Add-ADGroupMember -Server "domainB.com" -Identity $G.Name -Members $domainDNUser -Credential $creds -Verbose}
}

Answer 1

What are you doing?
You export to csv, but still try to save it to a variable
You search twice
You add all members from ALL groups in TEST-OU to every group in domainB
You waste time on saving and reading data that you already have in memory
You search for the user-object to get SamAccountName when you already have something ten times better, the DN. Then you use that SamAccountName to find the DN.
Try this (untested):
$creds = Get-Credential
$Groups = Get-ADGroup -Properties Members -Filter * -SearchBase "OU=TEST,OU=Shop Print Groups,OU=User,OU=domain Groups,DC=domain,DC=com"
Foreach($G In $Groups)
{
#Display group members and group name
Write-Host $G.Name
Write-Host "-------------"
$G.Members
#Add members to domainB group
$G.Members |
Get-ADUser -Server fairfieldmfg.com |
ForEach-Object { Add-ADGroupMember -Server "domainB.com" -Identity $G.Name -Members $_ -Credential $creds -Verbose }
}
I used a foreach-loop to run the Add-ADGroupMember because it usually fails in the middle of a group of members if it finds on the already is a member, but if we add them one at a time you get around that (or you could do a search and exclude those already in the group).
You may want to add -ErrorAction SilentlyContinue to Add-ADGroupMember to ignore those errors when you know the script works as it should.