Importing one subsidiary data from Production to Sandbox

Hi everyone, we have one particular requirement for our NetSuite instances. We want all the data in production of one particular subsidiary's data to our Sandbox instance. We don't want to import any other data apart from that particular subsidiary. What would be the best approach to do this. We don't want to refresh the Sandbox because of data security reasons. Please let me know what would be the fast, efficient and safe way to do this. Thanks.