Using a Powershell returns true script to not duplicate run

Question

I have created a Custom action to create some "standard" sub OUs to a particular type of OU in our AD. I wanted to create a script to look in the OU you are executing against and not run again if ANY of the sub OUs exist. I want something like below but I am not sure how to get $OU to have the appropriate collection.

foreach ($child in $ou)
{
if(($child.Name -eq 'Groups') -or ($child.Name -eq 'Users') -or ($child.Name -eq 'Computer Systems'))
{$Context.ConditionIsMet = $False }
}