TOPPER Mortimer has himself a new squeeze. The blueblood, recently separated from Tinsley Mortimer, has been making the Fashion Week rounds with Vogue editor Valerie Boster. “They were at the Paper magazine party looking smitten, and then he accompanied her to a party at Indochine,” says a source. As for Tinsley, who’s dating a London-based Prince Casimir zu Sayn-Wittgenstein-Sayn, we hear her reality show needs help. “The problem is she’s not dynamic enough on her own, so they’ve been putting out invitations to other socialites to be on camera with her,” said one insider. “Except no one legitimate wants to do it, so they may have to ‘create’ socialites for Tinz to hang with.”