[c] Both grandfather and adopted grandfather were sons of Frederick Frelinghuysen, the eminent lawyer who was one of the framers of the first New Jersey Constitution, a soldier in the American Revolutionary War, a member of the Continental Congress, and a member of the United States Senate.

[6] His maternal grandfather George Griswold,[3] was a merchant in New York City who "made an immense fortune in the time of the clipper trade with China.

[2] Upon his marriage in 1885 to Alice Coats, his mother and father-in-law wanted him to be brought into Auchincloss Brothers as an equal partner.

[28] Alice was the daughter of Sir James Coats, 1st Baronet and Lady Sarah Auchincloss, an American.

[2] Together, Theodore and Alice were the parents of:[30] After Alice's death in 1889, he married Elizabeth Mary "Lily" (née Thompson) Cannon (1871–1967),[34] the widow of Henry Le Grand Cannon,[3] on June 2, 1898, at Grace Episcopal Church in New York City by Bishop Henry C.

[2] After their marriage, they lived at her home, 60 Fifth Avenue and maintained a winter residence in Palm Beach, Florida, known as "Southways,"[35][d] and another house at Tuxedo Park, New York.

[1] His widow lived at their Palm Beach home until her death in 1967, at the age of 97, when she was referred to as "a grand dame of a bygone era.