(b) Subject to the same limitation the term "wages" includes also all compensation paid by an employer to persons in his employ with respect to which he is not liable for contributions under any other unemployment insurance law, even though such compensation is not remuneration as defined by section five hundred seventeen of this article, or the services of such persons are not in employment as defined by section five hundred eleven of this article, if the employer is liable for a tax on such compensation under the federal unemployment tax act. 2. Joint consideration. If an employer has acquired all or substantially all, or a segregable portion of the assets of another employer liable for contributions under this article, or has acquired all or a segregable portion of the organization, trade or business of another employer liable for contributions pursuant to subdivision seven of section five hundred eighty-one of this article, remuneration paid by both employers shall be deemed paid by a single employer for the purposes of this section.