Complex sentence: Throughout, Livingstone continued to try to revive the NHA, demanding and convening meetings on September 20 and December 11,1919, at which representatives of the Canadiens, Senators and Wanderers determined to close out the expired league for good.
Split into simpler sentences: Throughout, Livingstone continued to try to revive the NHA. He convened league meetings on September 20 and December 11,1919, at which representatives of the Canadiens, Senators and Wanderers determined to close out the expired league for good.