Frederick and Fredricka Dreer were married in Hanover, Pennsylvania, in 1796. Their first son Frederick Oberthier (1797-1856) was born in Pittsylvania, Virginia, and married Sarah Hubbard (1808-1882) in 1825.
- Augusta Elizabeth (1825-1888), who married John B. Matherly
- Mary Caroline (1827-1876), who married Charles S. Haydn in 1852
- Henry L. Dreer (1829-1904), who married Eliza Virginia Jones
- Sarah Ann (1830-1858), who married Rufus R. Collier
- Tabitha Hubbard (1833-1857), who married William A. Johnson
- Ferdinand (1835-1858)
- Frederick Harrison (1838-1913)
- Moses Allen (1840-1864)
- Benjamin Constant (1843-1911), who married Mattie Jane Wright
- Edward Chester (1846-1829), who married Margaret Gray
- Abigail Selena (1848-1878)
Most of the Dreer family, including Mary and Charles Haydn, moved to Canton, Texas, in 1852 in order to escape debt and to find better land on which to farm. Henry, the eldest son, traveled through the south looking for employment and ended up in Philadelphia in the 1850s. Several of the children died in Texas in the decade after the move, while others settled and raised families in Rusk County, Texas.
Another son of Frederick and Fredricka Dreer was Henry A. Dreer, born in 1819. He established a seed house in Philadelphia in 1838, and married Mary Leavenworth in 1847. Henry died in 1873.
In their letters, Frederick, Fredericka, and Henry use the last name Dreer, while the family of the eldest son Frederick went by Oberthier. Genealogical and census records largely support this, though Frederick and Fredericka Dreer are also referred to as Oberthier.