I altered the pattern slightly changing the fastenings.
For the shoulder straps I added a loop on each side of the front flap instead of the button, and fed the straps through before looping them back to button up. The boys have had dungarees with straps like this that were really secure. It's really easy to lengthen or shorten the straps by moving the button. The hips were a simple switch from button and buttonhole to a snap popper.
Next up: matching dungarees for the new baby cousin, Nickname still to be determined.