How can I ensure my BIP report for line managers only returns results of their reporting line?

Summary:

I've built a BIP report and made it available to managers as a link (static URL page entry in My Team) and it works perfectly except it returns results for all employees instead of only employees in their hierarchy. I expected the results would be based on their data access. Any ideas on how I can modify the SQL to only return results for their hierarchy without me having to add parameters? Are there certain tables that I should be selecting from that secures access this way? I cannot build an OTBI report for this (no subject area containing career