The lock point is concealed behind the bib and can be revealed by clicking on any of the sensing zones. Feel free to adjust their size and shape to your liking.
While the dress is a fitted mesh, it is not the case of the sensing zone prims or the padlock. Because every avatar is different, the shape of your avatar's torso will determinate where the locking post will be. Adjusting the position of the padlock is easy if you have a little bit of experience adjusting attachments: