Looking through all my Ivins stuff to find William Chapman and Sarah Ivins for you. I found the marriage for them in a book that I have for Dawn. I am pretty sure that Sarah Ivins is the daughter of Samuel Ivins and Sarah Platt that were married, December 20, 1766 in Burlington County, NJ. The name Chapman is used as a middle name a couple of generations down from the son of Samuel Ivins and Ann Rickey, which would be the brother of your Sarah Ivins Chapman. I have alot of records for this area including Hornerstown, Monmouth County, NJ, will look some more to see if your names turn up.