Sønder-Sejerslev was formerly part of the German Empire. In the German Empire, the place was called Süder-Seiersleff.
The place is now called Sønder Sejerslev and belongs to Denmark.
| Historical place name | Country | Administration | Time |
|---|---|---|---|
| Süder-Seiersleff | German Empire | Tondern | before the Versailles Treaty |
| Sønder-Sejerslev | Denmark | Tønder | after the Versailles Treaty |
| Sønder Sejerslev | Denmark | Sønderjylland | 1993 |