Find users and groups in all domains of my organization - powershell

Question

I need help finding users/groups that fall under multiple domains in my organization. As I have it right now it only looks through the main domain. I would want it to search for users/groups in all of my organizations domains.
This is what I have:
$Users = #()
$Groups = #()
$list = Get-Content C:\temp\ADGroups.txt
Foreach ($o in $list){
$ObjectClass = (Get-ADObject -Filter {SamAccountName -eq $o}).ObjectClass
If ($ObjectClass -eq "User")
{
$U = Get-ADUser -Properties * -Identity $o
$User = "" | Select FullUserName, LoginID, Description
$User.FullUserName = $U.DisplayName
$User.LoginID = $U.SamAccountName
$User.Description = $U.description
$Users += $User
}
Else
{
If ($ObjectClass -eq "Group")
{
$G = Get-ADGroup -Properties * -Identity $o
$GM = Get-ADGroupMember -Identity $G.name -Recursive | Get-ADUser -Properties *
Foreach ($gmember in $GM)
{
$Group = "" | Select GroupName, GroupDescription, GroupMemberName, GroupMemberLoginID, GroupMemberDesc
$Group.GroupName = $G.Name
$Group.GroupDescription = $G.Description
$Group.GroupMemberName = $gmember.Name
$Group.GroupMemberLoginID = $gmember.SamAccountName
$Group.GroupMemberDesc = $gmember.Description
$Groups += $Group
}
}
}
}
>> $Users | Export-Csv C:\temp\PCMUsers.csv -NoTypeInformation
>> $Groups | Export-Csv C:\temp\PCMGroups.csv -NoTypeInformation

Answer 1

Going off of TheIncorrigible1 comment, here is some code to accompany which may be useful.
$Domains = (Get-ADForest).Domains.ForEach{(Get-ADDomain $_).PDCEmulator}
$Users = #()
$Groups = #()
$list = Get-Content C:\temp\ADGroups.txt
ForEach ($dom in $Domains) {
Foreach ($o in $list){
$ObjectClass = (Get-ADObject -Filter {SamAccountName -eq $o}).ObjectClass
#Gets the users in that directory according to the ObjectClass rules
Get-ADUser -Identity $ObjectClass -Server $dom -Properties *
#....
}
}
#....
#....
Note: I don't have the AD-Module installed so I couldn't test it. let me know if it fails