NeophyteAssume the main DS you're having difficulty with is Microsoft_SQLServer_Databases, that method should work because of this line:
def sqlInstances = hostProps.get("mssql.sql_server_instances") ?: hostProps.get("auto.sql_server_instances") // override sql instances with manual instances
Take it back to the source and test active discovery at the datasource to see if you get the same behavior. If you're still getting more than you wanted, I would next take the script to the script debug console and flip the debug boolean to true. That should give you more output to help figure out what is happening inside the script and where the problem might be.
