$srcuser = "goldorak"
$trgtuser = "albator"
Get-DistributionGroup -ResultSize unlimited -OrganizationalUnit "domain.local" | foreach {
$groupname = $_.name
Get-DistributionGroupMember -Identity $groupname | Where-Object { $_.Alias -eq $srcuser } | foreach {
$groupname
Add-DistributionGroupMember -Identity $groupname -Member $trgtuser 
#Remove-DistributionGroupMember -Identity $groupname -Member $srcuser
}
}