CHAMPLAIN, Lydia, d. [John & Abigail, late of R. I.], b. Aug. 29, 1816
It appears that the editor's notation of her parents has an error, as Abigail was deceased and John was married to Martha by this time. This is confirmed by Lydia's gravestone.
includes a photo of her gravestone with the inscription: "In memory of Lydia Champlin daughter of John and Martha Champlin who died Jan. 31, 1841 aged 24 years"