I have a very simple app.  I have a table of organisations and a table of contacts.  Contacts are a subform of organisations.  So I can easily create contacts specific to an organisation.  As you can see in my screenshot my organisation Great Orthopaedics has two contacts - John and Jane.

Now I have another subform of Tickets - linked to the Organisation.  For a Ticket I want to be able to select a Contact from the organisation.  However it shows ALL the contacts in the system - not just those for the Organisation.  How can I fix this?