Additional or substituted underwriters shall be bound in the same manner and to the same extent as original subscribers to the articles of agreement and power of attorney on file with the Insurance Commissioner; and the acts of the duly-appointed deputy, substitute or successor attorney or any attorney or attorneys licensed under this chapter, accepting powers of attorney from underwriters, and in making and issuing policies and contracts of insurance, and in doing any additional acts incident thereto, shall be deemed authorized by the license issued to the original attorney or attorneys.