Series III. Phillips Family Relatives, 1809-1943, contains the papers of Stephen C. Phillips' sons: Stephen Henry Phillips (1823-1897), Willard Peele Phillips (1825-1901), and George William Phillips (born 1827); and the papers of grandson Stephen Willard Phillips (1873-1955).

Subseries A. Stephen Henry Phillips extends from 1846 to 1890, the bulk related to his 1883-1884 work representing the United States in Alabama claims cases. These papers involve claims made by fishermen who suffered damages incurred by Confederate vessels.

Subseries B. Willard Peele Phillips, 1849-1871, includes accounts of the ship Elizabeth, originally owned by his father (see Stephen Clarendon Phillips Papers for papers of the vessel prior to 1849). Papers as Collector of Customs, a position Willard held from 1861-1865, are comprised mainly of petitions for the position of inspector at Beverly and Salem. His business, civic, and personal correspondence include evidence of his interest in capturing Confederate privateers and the Barton Square Independent Congregational Church. Also here are his licenses and tax receipts as a wholesale dealer and the bills from the estate of his father-in-law Francis Boardman.

Subseries C. George William Phillips includes a diary which documents his years at Harvard University (1844-1847) and his job at the Essex Railroad Office in 1846.

Subseries D. Stephen Willard Philips, 1902-1943, consists primarily of the collection of funds and the restoration of the Peirce-Nichols house, an Essex Institute project of which he was the treasurer. Also included are miscellaneous letters regarding his donations to the Essex Institute and other individuals.