There has been discussion on the TL list about Sit and the "drop back" sit ... which is the way Lily sits. That has led me to think about using a target or a perch to retrain Lily's Sit, teaching her to keep her front paws in position and bringing her back end forward into a sit.
By using a perch target for the Sit I can also use it to strengthen her Down. Marge has two good videos demonstrating this form of "perch" training. Sheila uses it also.