Homeowners at the Landing at Dobbs Ferry found a way to minimize the impact of a new federal tax law last year by converting their homes to condos.  But when they tried to make the conversion to save about $1 million a year on property taxes, local government officials and the New York State attorney general, they claim, thwarted their plan.  On Monday, the homeowners’ association sued Attorney General Barbara D. Underwood in Westchester Supreme Court to compel her to recognize the Landing as a condominium.    Read the article………………