According to numerous sources, including the First Presbyterian Church of Morristown,NJ, (of which Sarah Condict Howard and her husband Shadrach were members of and had all their children baptized there), they are most certainly buried there in unmarked graves (of which the church records say there were many unmarked graves), as they are recorded in the church records there.
Sarah was of Peter Condict (of Peter, of John @ FAG memorial # 12179447)which is indexed as Condit in the Condit authored/indexed genealogy books, although contrary to the actual, historically recorded surname in NJ Archives. Her husband is found in the Morris clan books ( dot com), as Shadrach Howard (b. 1724, d.1790, Oct. 21.
Their children were: Bethuel Howard, Eunice Howard, Isaac Howard, Rebecca Howard, Rhoda Howard, William Howard.
Rebecca,b. march 21, 1757; Bethuel, Oct. 14, 1759, b. @ FPChurch. All children were baptized at the First Presbyterian Church and are in the church records.
The Morris Clan also shows the records, where the Howard family came from England and cited as: The family of Morrice (Morris) was of great antiquity, traced in lineal descent from Athelstan Glodrydd, Prince of Ferlex, betwist Wye and Severn, who sprang from the old Princes of Powys, and who through his mother, Fheingar, daughter and heir of Grono as (son) Tudor Trevor, an eighth in a direct line from Caradac Vriechfras, Lord of Hereford, one of the Knights of King Arthur's Round Table (540 A.D.) Athelstan Glodrydd was godson of Athelstan, King of England (924 A.D.) and founded the fourth Royal tribe of Wales. His grandson Holdliw was Prince of Ferlex, according to Burke's Book of Commoners.
Shadrach is listed in the The Howard Families of New Jersey, the Morris Clan. Bio written by a descendant.