Help with triggers, please!

Let me explain my business problem and then show you my solution (which doesn't work). I want to take ISAM databases and convert them into their normalized, relational-world equivalent tables. I created 6 tables, one to emulate the exact structure of the original ISAM db and five new relational tables with constraints, etc. I created an INSERT trigger on the ISAM-structured table so that each time a row was inserted into it (LOADing from a delimited file) there would be a corresponding insert into each of my relational tables. My first problem was that I had duplicate keys in one of the tables (which I expected) and the load aborted. Then I spent half a day figuring out how to use the "FOR EACH ROW WHEN" structure to only insert when a record with the same key did not already exist. It worked when I updated a single table, but when I went to add another "FOR EACH ROW" in the trigger it wouldn't allow it. I need to have specific "WHEN" conditions for each of these tables because there is a potential for duplicate keys in almost all of them. Can anyone explain a better approach, or perhaps clue me in on how to modify my current approach. I would be most appreciative. Thank you for your time. The following is my trigger code for updating one table (which works): CREATE TRIGGER createsqltablesINSERT ON prtded REFERENCING NEW AS new FOR EACH ROW WHEN (NOT EXISTS (SELECT * FROM group WHERE group.group_id = new.group_no)) ( INSERT INTO group (group_id) VALUES (new.group_no) );