Dear, WJ Hank,
Estellville is not a part of Hamilton Twp, it's a part of the city of Estell Manor, just south of Mays Landing, about 10 miles east of Vineland. Estellville was never a part of Winslow Twp or Camden County, unless if you want to count when the areas that are now Camden, Gloucester and Atlantic counties were all called Gloucester county. I'm not sure when Camden county stood on it's own, but I do know that Atlantic was it's own by 1826.
If you want to know anything else about Estellville, I could probably help you out. I grew up in Estell Manor and my family still lives there--my mother even helped found their historical society back in the 80s.
HL Bock :)