Harry Morton is doing his best to be a good influence on girlfriend Lindsay Lohan. Morton's half-sister was Domino Harvey, the model-turned-bounty hunter played by Keira Knightley in a film last year, and who died about a year ago after a longtime substance abuse problem. Lohan's new beau wants her to be sober, according to a friend, and the Mean Girls actress has vowed that "she will stay away from booze altogether." Another source said, "She's not drinking. I've never seen her so healthy and happy."source