Phil - Further to an earlier discussion:
I'm back to this and am attempting to try your suggestion. Much earlier you mentioned:
You can allow creation in this relationship and then this script step:
Set Field [Table3 (2)::Field ; Table2::Field ]
Will create a new record in Table 3 if no matching record exists. It will update a matching record if at least one matching record does exist. (It will update the first such related record.)
Would the script be triggered upon exit of the portal row (which is a record in Table 2 in a portal in Layout 1)?
Also...should the layout for Table 3 be based on the table 3 TO that was created?