Here's a list of Stefano's spawn:
Tony (alive) - found out he wasn't Stefano's son as an adult when Daphne admitted she had an affair with the gardener
Andre (dead) - found out as an adult he WAS Stefano's son because Stefano had an affair with his sister-in-law (Andre's unnamed mother)
Renee (dead) - found out she was Stefano's daughter as an adult; Renee thought Lee DuMonde (her mother) was her older sister
Megan (alive) - we never found out what her backstory was, who her mother was or how she knew Stefano was her father and that Maxwell Hathaway was just pretending to be her father (we only knew she grew up in Salem and went to high school with Bo; they were high school sweethearts)
Benjy (dead) - Stefano was married to Benjy's mother, Ellen Hawk (he was presumed dead in Salem at the time and married her using the name David Hadley) and Stefano raised Benjy from birth until Ellen took Benjy and went on the run to keep him safe (Shane's twin brother Drew killed Ellen)
Lexie (dead) - She didn't find out Stefano was her father until she was an adult (Celeste was her mother)
Peter and Kristen (alive/alive) - he adopted them as kids after the supposed death of their mother, Rachel (there's a lot of back/forth as to whether he adopted them or was just their guardian, but I have the video clip of Kristen telling John that Stefano adopted her as a child, using the word "adopted")
EJ (alive) - Stefano knew from the beginning EJ was his child. Susan and Edmund took baby EJ to England and raised him. We don't know at what point Stefano got his hands on EJ again, but EJ did occasionally mention growing up with Edmund as a loving stepfather
Chad (alive) - found out he was Stefano's son when he was a young man and that his mother Madeline had been a hooker to put herself through law school
Stefan-Zero and Jake - (alive/dead) - found out as adults they were the twin sons of Stefano and Vivian
Grandchildren:
Steven Hawk (Benjy's son) (alive)
Theo Carver (Lexi's son) (alive)
Rachel DiMera Black (Kristen's daughter) (alive)
Johnny DiMera and Sydney DiMera (EJ's children) (alive/alive)
Grace Brady, Thomas Deveraux and Charlotte DiMera (Chad's children) (dead/alive/alive) (NOTE: Chad had Thomas' birth certificate changed to have his last name be Deveraux because he thought it was a better name to have in Salem than DiMera, but I guess the writers have forgotten that)