Sydney Ann DiMera is the daughter of EJ DiMera and his ex-wife Sami Brady. She is the younger sister of Will Horton, Allie Horton, and Johnny DiMera. She is the legal older sister of Grace Brady. While Sami was pregnant, Nicole had miscarried her daughter with EJ and need to have a baby.
Nicole planned to adopt Grace but Nicole learned that Sami gave birth the same night that Mia did and switch the babies. When Grace died, EJ and Sami learned that Grace was not their daughter and Sydney is. Nicole made a run with the little girl. She was later kidnapped by Anna DiMera. It was later revealed that she was kidnapped by her father and Anna in attempt to reunited her mother and her father. Sydney was born on January 23, 2009.
- Avery and Cade Seger (January 2009 - Ferbruay 2009)
- Hailey and Lauren Sinnema (February 24, 2009 - present)
- EJ DiMera (father)
- Sami Brady (biological mother)
- Nicole Walker (legal mother; rights taken after the switch was revealed)
- Rafe hernandez (step-father)