Have you selected the Subform object or the form inside the object?

I've looked in the property lists both for the FamilyMemberF by itself and in the when it is a subform in the ExtendedCustomerF and the property list for the ExtendedCustomerF.  I can't find the Linked Master or the Linked Child property in any of these property lists.  As I said, when I insert the subform using the wizard, the link seem to be made automatically.