There are tombstones for Jackson, Elizabeth & Sarah Jemima Watson buried in Highland Cem., Lock Haven, PA. If Martha Billet was buried here at L.H., her obit maybe in Ross Library file & or in one of the Funeral home records. Also any moument service would know who to contact for you. Such as Gibson Monuments, Route 150, Mill Hall, Pa 17751, 570-726-3602. There are Watson & Billets in Cedar Hill cem., Mill Hall, R.D., PA, also, they were mostly from Porter Twp., Clinton Co., PA. Jackson had 4 other girls & 1 son as recorded in 1870 Lock Haven Census.