Section 29. The first justice of the Middlesex county court may, with the approval of the chief justice of the probate and family court, appoint a clerk who may administer the oaths required in probate proceedings that are not prescribed by law to be administered by the judge or register and shall perform such clerical and other duties as may be required by the first justice. The clerk may be removed by the first justice with the approval of the chief justice. The register may, with the approval of the chief justice, designate 6 employees as deputy assistant registers with the same powers as assistant registers and with the approval of the chief justice remove a deputy assistant register. The deputy assistant registers shall receive additional compensation in an amount equal to 15 per cent of the annual salary of the Middlesex county register of probate.