sentences:  During the reign of Casimir Jagiellon it was renamed to the Council of Lords.Under the Union of Lublin of 1569, the Council formally became a constituent part of the Polish–Lithuanian Senates (see also Offices in the Polish-Lithuanian Commonwealth), together with the Royal Council of Poland, but it continued to operate "de facto" until the mid-17th century.The Council carried out the functions of the Grand Duke after his death and had a supreme authority in the Grand Duchy of Lithuania until a new Grand Duke was appointed, as well as organised his appointment.