(1) the effective date of the original certificate of limited partnership; or
(2) the date as of which the person becomes a limited partner pursuant to the partnership agreement; provided, however, that if such date is not ascertainable, the date stated in the records of the limited partnership.
(b) After the effective date of a limited partnership's original certificate of limited partnership, a person may be admitted as a limited partner:
(1) in the case of a person acquiring a partnership interest directly from the limited partnership, upon compliance with the partnership agreement or, if the partnership agreement does not so provide, upon the written consent of all partners; and
(2) in the case of an assignee of a partnership interest of a partner who has the power, as provided in section 121-704 of this article, to grant the assignee the right to become a limited partner, upon the exercise of that power and compliance with any conditions limiting the grant or exercise of the power.