Final answer:
The provided information does not address the specifics of the 1961 Washington D.C. Grand Conclave but focuses on the 1787 Constitutional Convention and the principles and procedures for amending the U.S. Constitution.
Step-by-step explanation:
The question regarding the 1961 Washington D.C. Grand Conclave seems to be seeking information on an event related to a specific organization or group, particularly asking about the attendance of founders and former Grand Basilei. However, the information provided doesn't directly address this event or provide sufficient details to answer those specific attendance questions. Instead, the provided information focuses on the Constitutional Convention of 1787 and the drafting of the United States Constitution. Regarding the guiding principles of the Constitution, these include establishing justice, ensuring domestic tranquility, providing for the common defense, promoting the general welfare, and securing the blessings of liberty. The Constitution can be formally amended through the process outlined in Article V, which requires a proposal by a two-thirds majority in both the House of Representatives and the Senate, followed by ratification by three-fourths of the state legislatures or conventions. It can also be informally amended through judicial interpretation, legislative action, and social and cultural shifts that influence the way the Constitution is understood and applied.