creating portal using mulitple fields for relationships

[duckster]

Hi. I'm a new user to FileMaker 6.0 on Mac. I've got three databases containing patient information from our rehabilitation centre. All of the databases have clinical information for each patient but we report the information to 3 different insurers. Therefore there are three separate databases (each patient has a patient_id field in each database). I didn't create these databases and I'm not sure if this is the best way to set it up but that's how it is and my employer does not want to make major changes to these databases.

I want to create a new database that contains results of a series of functional tests (ex. lifting, carrying, pushing/pulling, etc). This database would have a number of records for each patient, each record representing a different functional test. I suppose I could go into each database and create a bunch of new fields but this would be redundant and not all patients need to perform the testing. Not only that, the number of tests for each patient will vary. The functional testing information we report is the same across insurers.

For each of the three databases, I would like to create a portal that allows me to add/view records from the new (functional testing) database. I created a patient_id field and an insurer field in this new database. For each of the three datbases if I create a relationship using patient_id, then I will see all of the records for a particular patient_id, regardless of insurer. How do I create a relationship that allows me to view/add portal records for patient_id & specific insurer. Make sense at all? Is there a tutorial or file somewhere that will explain relationships for multiple fields? Thanks for your help.