Daphne DiMera was never actually married to Stefano, but lived with him so long she ended up taking his name. She watched Stefano cheat on her for years with various women, and watched him turn the children from those relationships into clones of himself. When Daphne learned she was pregnant, she took off, unwilling to let Stefano corrupt her child. Antony DiMera was born and raised in Australia, but Stefano eventually took him back into the fold. Years later, Daphne tracked her former lover and son to Salem, and Tony saw just how much his absence had affected his mother, and took her to see Dr. Marlena Evans. Daphne's ramblings made no sense...she went on and on about how evil Stefano was, but how wonderful Tony's father was. Desperately trying to comfort his mother, Tony began telling her all about his life, including his romantic feeling for Rençe DuMonde, a woman he'd recently learned was his sister, and who was about to marry another man. When she heard this, Daphne confessed her greatest secret...Tony's father was, in reality, a man named Enrico, whom Stefano had killed when he learned Daphne was sleeping with him.
Tony immediately checked this by comparing his blood type with Stefano, which convinced him that his mother's tale was true, and he was indeed free to be with Rençe, but Daphne warned Tony he must never tell Stefano, because Stefano would kill them both. (When Tony returned to Salem in the 1990s, the storyline was changed, and he was biologically proven to be Stefano's son. No mention was made of Rençe at that time.) Unfortunately, Stefano began to realize something was wrong, and confronted Daphne, who admitted the truth. Before Stefano could really do anything, he 'died' of a stroke. Daphne recovered rapidly, and left the hospital, to move into the mansion. She did her best to get Tony and Rençe together, even though Rençe was married to another man, but her plans fell through when Tony eloped with Anna Fredericks, who soon claimed to be pregnant. Daphne couldn't do anything about this, so she started meddling in Liz Chandler's life, and when Liz, who had an affair with Neil Curtis (in part at Daphne's urging) accidentally shot Marie Horton, Daphne helped her cover it up, until Roman Brady threatened to deport her if she didn't talk.
When Daphne uncovered a second will that left everything to Rençe, she was desperate to get Rençe and Tony together. She succeeded on that count, as the two soon announced their engagement, but Rençe had discovered the truth, and told everyone that night at the engagement party. When she was found dead the next day, Daphne was a prime suspect, until they discovered that it was, in fact, Tony's cousin Andrç, one of Stefano's many nephews, who had gotten plastic surgery to look like Tony. Daphne spent much time traveling after this, and was responsible for bringing Kimberly Brady back from Europe. Once she returned, she received an unusual necklace in the mail, not realizing it was the second of the three prisms that everyone was looking for. She agreed to let Calliope Jones use it in a Haitian photo shoot, as long as she got to go along. Unfortunately, the plane crashed, and Daphne died in the arms of her son, Tony...realizing at the last second that it was actually Andrç who held her in his arms, but unable to tell anyone.