David M. Ehrlich, a New York attorney, wanted to become business manager for one of his clients, Lauren Spencer-Smith, when her singing career started taking off. So he advised her to obtain independent counsel to review a proposed management agreement. But he also took the risk of recommending two attorneys. And the one she hired, Jonathan Horn, was allegedly “a personal acquaintance of Ehrlich’s.”Suing Ehrlich and his law firms for alleged breach of fiduciary duty, Spencer-Smith alleged she didn’t have genuinely …