Hello Debbie,
As far as i understand your problem, you should no link table "Passengers" to table "Diagnosis directory".
As Adam said, you should define a rollup field in table passengers as such:
I copied your base and modified the Flight requests in order to have 3 different diagnosis on 3 different lines for Bobba Flett, here is the result in passengers tables:
If needed, you can also filter this "diagnoses" rollup field to show only diagnoses for which status is either "In progress" or "Booked" in "flight requests" table:
Regards,
Pascal