Through his daughter Gertrude, he was the grandfather of Gertrude Hubbard Grossmann (1882–1919), who married Peter Stuyvesant Pillot (1870–1935), at Hubbard's home, Twin Oaks, in 1903.
Their daughter, Rosalie Pillot (1907–1959) was married to Lewis Rutherfurd Stuyvesant (1903–1944), the son of Rutherfurd Stuyvesant, in 1925.
 After giving birth to a son, they divorced in 1935.

Through his daughter Mabel, he was the grandfather of Elsie May Bell (1878–1964), who married Gilbert Hovey Grosvenor of National Geographic fame, Marian Hubbard "Daisy" Bell (1880–1962), who was married to David Fairchild.
and two boys who died in infancy (Edward in 1881 and Robert in 1883).

Through his daughter Roberta, he was the grandfather of Grace Hubbard Bell (1884–1979), who was married to Granville Roland Fortescue (1875–1952), an American soldier and Rough Rider who was the cousin of Theodore Roosevelt and son of Robert Roosevelt (born while his biological father was married to his first wife but adopted by him following her death and his marriage to his mother).
 Grace was the mother of three girls, Marion Fortescue, who married Daulton Gillespie Viskniskki in 1934, Thalia Fortescue Massie (1911–1963), and Kenyon Fortescue Reynolds (1914–1990), better known as actress Helene Whitney.
Through his daughter Gertrude, he was the grandfather of Gertrude Hubbard Grossmann (1882–1919), who married Peter Stuyvesant Pillot (1870–1935), at Hubbard's home, Twin Oaks, in 1903. Their daughter, Rosalie Pillot (1907–1959) was married to Lewis Rutherfurd Stuyvesant (1903–1944), the son of Rutherfurd Stuyvesant, in 1925.  After giving birth to a son, they divorced in 1935.
Through his daughter Mabel, he was the grandfather of Elsie May Bell (1878–1964), who married Gilbert Hovey Grosvenor of National Geographic fame, Marian Hubbard "Daisy" Bell (1880–1962), who was married to David Fairchild. and two boys who died in infancy (Edward in 1881 and Robert in 1883).
Through his daughter Roberta, he was the grandfather of Grace Hubbard Bell (1884–1979), who was married to Granville Roland Fortescue (1875–1952), an American soldier and Rough Rider who was the cousin of Theodore Roosevelt and son of Robert Roosevelt (born while his biological father was married to his first wife but adopted by him following her death and his marriage to his mother).  Grace was the mother of three girls, Marion Fortescue, who married Daulton Gillespie Viskniskki in 1934, Thalia Fortescue Massie (1911–1963), and Kenyon Fortescue Reynolds (1914–1990), better known as actress Helene Whitney.
Gardiner Greene Hubbard