You need to add the third parameter when you update the query to include it. That is why you got the error. It is probably best to update it in the Recordset server behavior if you aren't familiar with updating the recordset code by hand.
The query would be something like:
SELECT id FROM artworks WHERE position > colname OR (position = colname2 AND id > colname3) ORDER BY position, id LIMIT 1
With the sql parameters and runtime values of: colname = $_GET['position'], colname2 = $_GET['position'], colname3 = $_GET['id']