Meloni is the daughter of President Thawne, a descendant of the Reverse-Flash. She married Don Allen, to try and end the millennium long feud between the Allen's and the Thawne's, and had their son, Bart Allen. Her husband died in the Dominators invasion, and she was told her son died in the invasion as well, but actually he was placed in a virtual reality by his grandfather, to try and slow down his accelerating aging. He was later freed and taken to the 20th century. But, after Bart became Impulse, President Thawne became disappointed that Bart continued the Flash legacy and created a clone of Meloni's son, named Thaddeus.
It is later revealed that Meloni is the mother of Owen Mercer, the son of the original Captain Boomerang, Digger Harkness. She conceived Owen when Digger was trapped in the 30th century. It's unknown who was born first, Owen or Bart, or how Owen came to be in the 20th century.