I recently inherited a database for a local New Mexico college in Santa Fe, something I always enjoy. I like to learn, and I try to learn at least one new thing a day (that's the absolute minimum, actually).
This database taught me something I had not seen in all my years as a FileMaker developer. And that made me want to share it.
The heart of this trick is simple: use a relationship set on the fly to add a new record to a related table. The twist: it's not added through a portal, nor is it added through the other usual method: freeze the screen, go to the proper layout, make a new record, use variables to set key values, etc.
Instead, this system set a key value to match the other side of the relationship, this making a link to the table with the ability to add a record through this relationship. Once the key match is set up, simply use the Set Field command to update the foreign key from the current table. Very easy, very straightforward.