Dumitru Posmagiu was born circa 1865 in Niculești, Buzău County, Romania to Mihai Posmagiu (1827-1925) and Ana Unknown (1835-1905) and died circa 1935 Niculești, Buzău County, Romania of unspecified causes. He married Ana Cățoiu (c1875-c1940) .
Children
| Name | Birth | Death | Joined with |
| Niculae Posmagiu (c1898-1918) | 1909 Niculești, Buzău County, Romania | 1918 | |
| Nelly Posmagiu (c1900-c1920) | 1900 Niculești, Buzău County, Romania | 1920 | |
| Dumitru Posmagiu (c1905-c1925) | 1905 Niculești, Buzău County, Romania | 1925 | |
| Lucreția Posmagiu (1909-2001) | 1909 Niculești, Buzău County, Romania | 2001 Hamburg, Germany | Ion Coșoreanu (1903-1976) |
| Emilia Posmagiu (c1910-c1985) | 1910 Niculești, Buzău County, Romania | 1985 Romania | Cincinat Bocioacă (c1905-c1970) |
Siblings
| Name | Birth | Death | Joined with |
| Dumitru Posmagiu (1865-1935) | 1865 Niculești, Buzău County, Romania | 1935 Niculești, Buzău County, Romania | Ana Cățoiu (c1875-c1940) |
| Irina Posmagiu (c1867-c1930) | 1867 Romania | 1930 Romania | Victor Moisescu (c1860-c1925) |
| Caloian Posmagiu (1875-1955) | 1875 Buzău, Buzău County, Romania | 19 November 1959 Romania | Maria Pasăre (1881-c1940) |
| Alexandrina Posmagiu (c1880-1938) | 1880 Romania | 17 May 1938 Bucharest, Romania | Gheorghe Șerbănescu (1870-1949) |