### CREATE OVERRIDES FOR MONITORS, FOR SPECIFIC INSTANCE OF TARGET CLASS ###

Param(
$MS
,$cred = $(Get-Credential "MyDomain\Myself")
,$targetMPName = "My App - Overrides"
,$TargetContextComputer = "MyServer.MyDomain.home"
,$targetMonitorsPatern = "Check My App*"
,$OverrideProp = "Enabled"
,$OverrideValue = "True"
,$OverrideSuffix = ".Override_$OverrideProp`_$TargetContextComputer"
)

# Import of SCOM module
try
{
Import-Module -Name OperationsManager -ErrorAction stop
}
catch
{
write-host -ForegroundColor red "Error during import of SCOM module"
}

# Connection to management server $MS
New-SCOMManagementGroupConnection -ComputerName $MS -Credential $cred


# The target MP
 $targetMP = Get-SCOMManagementPack -DisplayName $targetMPName

 # The monitors 
 $targetMonitors = Get-SCOMMonitor -DisplayName $targetMonitorsPatern


foreach ($Monitor in $targetMonitors)
{

    if( $Monitor.AlertSettings.AlertOnState -ne $null)

    {
    $Target= Get-SCOMClass -id $Monitor.Target.Id 
    $TargetContextInstance = Get-SCOMMonitoringObject -Class $Target | Where-Object {$_.'[Microsoft.Windows.Computer].PrincipalName'.value -eq $TargetContextComputer}   # Get the Monitoring Object that match the $TargetContextComputer

    # Name of the override
    $overridename=$Monitor.name+$OverrideSuffix

    # Create Override and fill its properties
    $override = New-Object Microsoft.EnterpriseManagement.Configuration.ManagementPackMonitorPropertyOverride($targetMP,$overridename)
    $override.Monitor = $Monitor
    $override.Property = $OverrideProp
    $override.Value = $OverrideValue
    $override.Context = $Target
    $override.ContextInstance = $TargetContextInstance.Id
    $override.DisplayName = $overridename
    }

}

# Verify and commit the change
$targetMP.Verify()
$targetMP.AcceptChanges()