(Reuters) - Singer Barry Manilow on Thursday canceled the opening night and three other performances of his Broadway comeback run after coming down with bronchitis, according to Manilow's website. The cancellations threaten to upend the "Could It Be Magic" singer's return to Broadway following a more than two-decade absence. The concerts, which had been slated for Thursday through Sunday, will be made up in February and March, his website said. Manilow, 69, will try to perform on Tuesday, the next scheduled show. ...