Underhill Family

I am looking for people that are researching the family of one of Captain John Underhill's descendants - specifically the family of Jackson Underhill. I am trying to locate any information I can on Susan and Alice Underhill, who descend from Jackson and his wife Mary Lambertson. I have found some information online, mostly on Alice. Susan seems to disappear after the 1870 Federal Census. There is a reference in the Underhill Genealogy that lists her as being buried "in Hempstead." Since many Underhills are in the Greenfield Cemetery, it was thought that is where she is, but the cemetery has no record of her. If anyone has information that they are willing to share, I would be very appreciative.

Lori Pellnitz