(2) Every present or future estate shall be void in its creation which shall suspend the absolute power of alienation by any limitation or condition for a longer period than lives in being at the creation of the estate and a term of not more than twenty-one years. Lives in being shall include a child conceived before the creation of the estate but born thereafter. In no case shall the lives measuring the permissible period be so designated or so numerous as to make proof of their end unreasonably difficult. (b) No estate in property shall be valid unless it must vest, if at all, not later than twenty-one years after one or more lives in being at the creation of the estate and any period of gestation involved. In no case shall lives measuring the permissible period of vesting be so designated or so numerous as to make proof of their end unreasonably difficult.
New York Legal Code