It’s been more then one comic.
In infinite frontier thanks to the Black Lantern ring he learned that Lian is alive. Problem is he doesn’t know where she is only that she’s alive. Oh and Lian has amnesia so she doesn’t remember Roy or Cheshire. Apparently the events of Justice League cry for justice sort of happened, but Lian didn’t die, Cheshire just dropped her off at an orphanage.
So he’s asked his friends in the Titans and Jason Todd for help, they just haven’t found her. Though Cheshire has, though only in teaming up with Catwoman as Lian became Cheshire Cat, a sidekick to Catwoman.