Complex sentence: The Convention amended the admissions rule to require one-third of those voting to reject a new member and in 1972 the Supreme Convention again amended its rules to require a majority of members voting to reject a candidate.
Split into simpler sentences: The Convention amended the admissions rule to require a vote by one-third of those voting in order to exclude a potential new member. In 1972 the Supreme Convention amended its rules again, requiring a majority of members voting to reject a candidate.