Hmm....so why don't we move it to the 9th permanently? What would it take....a change in particular law?
The official Ruthenian recension books still have the Conception of the Mother of God on Dec 9. It was moved in the US by Bishops Stephen and Nicholas effective 1967: "... the Feast of the Immaculate Conception, since it is the patronal feast of the United States, will be celebrated on December 8 for the sake of uniformity of observance in this country"(The Liturgical Year of the Byzantine-Slavonic Rite by Basil Shereghy, Page 10).
Which in my opinion was a silly thing to do. What uniformity was established? They didn't make it a Holy Day of Obligation as it is in the Latin Church which was sson to declare they would move it to the Dec 9 if Dec 8 fell on a Sunday. It broke uniformity with the Ukrainians, Melkites, and every other Greek Catholic Church that didn't move the date.
It is time for the Council of Hierarchs to officially move the Feast back to Dec 9 so we can be in uniformity with our own tradition.