Populate existing array/table with new data - arrays

Question

I'm still at the beginning of learning powershell. My goal here is to have a script that pulls SCOM alerts that are one day old, compares the alerts' netbios computer name to a value from a CSV that I will import.
If the ServerName from the CSV Matches the NetbiosName it then adds the Administrator Name to the original Array/Table I created. Currently it does everything I ask of it, but when I have it output the final data it only has the last administrator that was used added to the Admin column instead of the appropriate admin.
NetbiosComputerName : Server
MonitoringObjectDisplayName : Server.Domain
Name : Blah Blah Blah
Severity : Warning
ResolutionState : 0
RepeatCount : 0
Server Adminstrator : Admin
NetbiosComputerName : Server
MonitoringObjectDisplayName : Server.Domain
Name : Blah Blah Blah
Severity : Warning
ResolutionState : 0
RepeatCount : 0
Server Adminstrator : Admin
On the Second output the Admin should instead reflect the admin for that particular server and not very same one.
Here is my code.
# Load SCOM snap-in
add-pssnapin "Microsoft.EnterpriseManagement.OperationsManager.Client";
$server = "RMSSERVER"
# Connect to OpsMgr SDK - change management server to your RMS
new-managementGroupConnection -ConnectionString:RMSSERVER.domain;
set-location "OperationsManagerMonitoring::";
$Date = (Get-Date).adddays(-1)
$ScomAlert = get-alert | where {($_.ResolutionState -eq 0) -and ($_.TimeRaised -gt $Date) } | Select NetbiosComputerName,MonitoringObjectDisplayName, Name,Severity, ResolutionState, RepeatCount
$Administrators = Import-CSV "C:\Script\SCOM\admin.csv"
$TableSC = $ScomAlert
ForEach ($Alert in $ScomAlert)
{
$NetBios = "$($Alert.NetBiosComputerName)"
$MonObjectName = "$($Alert.MonitoringObjectDisplayName)"
$AlertName = "$($Alert.Name)"
$Severity = "$($Alert.Severity)"
$ResState = "$($Alert.ResolutionState)"
$RepCount = "$($Alert.RepeatCount)"
ForEach ( $Admin in $Administrators )
{
$ServerName = "$($Admin.ServerName)"
$ServerAdmin = "$($Admin.AdminName)"
if($ServerName -eq $NetBios)
{
$ServerAdministrator = $ServerAdmin
}
}
$TableSC | Add-Member -MemberType NoteProperty -Name "Server Adminstrator" -Value $ServerAdministrator -Force
}

Answer 1

$TableSC | Add-Member -MemberType NoteProperty -Name "Server Adminstrator" ...
The above line replaces the property Server Administrator in all items of the collection $TableSC with the given value.
If you want each item updated with the respective administrator you need something like this (untested):
$Administrators = #{}
Import-Csv "C:\Script\SCOM\admin.csv" | % {
$Administrators[$_.ServerName] = $_.AdminName
}
$TableSC = $ScomAlert | select NetBiosComputerName,
MonitoringObjectDisplayName, Name, Severity, ResolutionState, RepeatCount,
#{n="Server Administrator";e={$Administrators[$_.NetBiosComputerName]}}