I am looking for any information on a Martha S. Cooper born about 1805 in NJ. I believe the S stands for Stillwell. She marries Cornelius Vanderbilt born about 1803 in NJ. They later move to Brooklyn NY. There are two Cooper relatives buried in a family gravesite with Martha S. Cooper-Vanderbilt. They are Joseph E. Cooper and Mary A. Cooper, although in the same family gravesite Joseph and Mary are not buried together. I think they might be siblings of Martha's. Any help would be appreciated.

Found answers to my own question:
Mary A. Cooper was her sister-in-law died 1890.
Joseph E. cooper was her nephew, died 1891.