How old are they?
Is Jaxson on meds for his reflux? It does sound uncontrolled to me...
If Molly finishes a 4 oz bottle, increase her feeds to 5 or 6 ozs and see what happens. You don't want them to drain bottles - you want them to stop eating because they are full and not because the food ran out... this is not a full feed and will cause snacking.