That's not how subforms work. When you retrieve a parent record, you also retrieve all of it's subrecords. FormResultSetCurrentPosition() just tells Sesame which of the retrieved child records you want to have displayed(Form View) or selected(Table view).

If you want to blank out the subform, you either need to delete all the child records, clear the child records, create a new child record so you're looking at a blank subform, or unlink the child records and reload the parent record.

-Ray