(b) An assignee who has become a limited partner has, to the extent assigned, the rights and powers, and is subject to the restrictions and liabilities, of a limited partner under the partnership agreement and this article. An assignee who becomes a limited partner also is liable for the obligations of his assignor to make and return contributions as provided in section thirty-eight of this article: Provided, That the assignee is not obligated for liabilities unknown to the assignee at the time he became a limited partner.
(c) If an assignee of a partnership interest becomes a limited partner, the assignor is not released from his liability to the limited partnership under sections fourteen and twenty-eight of this article.