Add-PSSnapin Quest.ActiveRoles.ADManagement
$AdminCredentials = Get-Credential "DomainAAdminAccount"
$list = Get-Content C:temppsMLSusers1.csv
$user = Get-QADUser $list -Service 'DomainA.com'$AdminCredentials
Add-QADGroupMember DomainBtestgroup $user

Import-module ActiveDirectory
Import-CSV "c:TempPSMLSusers1.csv" | % {
  Add-ADGroupMember -Identity testgroup -Member $_.UserName
}