Everything that occurred in the Spectre Hal series is unconfirmed reality--some things are supposed to be Parallax and Sinestro putting illusions in Hal's head. This is how Geoff resurrected Hal's brother, Helen's supposed father. Hal himself never refers to anything that happened when he was dead, mentioning when he was resurrected that he feels like he's been dreaming. I'm happier with the notion that Helen isn't abandoned somewhere..
Helen herself is problematic. She didn't exist before DeMatteis brought her in for the series, however, her clone existed in DeMatteis' Dr. Fate run. She could be easily fanwanked as some sort of cosmic child who shows up for super magicky cosmic types who need some grounding. In the Death miniseries, Death offhandedly remarks that the Universe arranged her life so she has a normal background despite just coming into existence, so there's precedence.