Doyle, first, I am not even close to being an expert on either the US Constitution or the Declaration of Independence. With that having been said, let me react to your post.

I believe the US Constitution, along with the Amendments and related case law (including derivative Public Laws) is the sole and only body of law governing what is and is not legal in the United States

I believe the Declaration of Independence is not law in this country. It is two things - a statement of the underlying causes and derivative rights related to America's secession from Great Britain and, as you say, a "foundation document," that much of the Constitution was predicated upon. That is all it is. Again, it is not law.

In short, provisions of the Declaration of Independence that did not find their way into the US Constitution do not, in my opinion, carry the weight of law.

Can you point to any historical document, just one, that even suggests, if not declares that a "Right of Secession" was at any time during the drafting of the Constitution and the Bill of Rights understood by any one involved in any way with the creation of either document to be an Amendment IX "other" non-enumerated right?

This, along with the philosophical conundrum I identified above, has been the source of much confliction in my mind for many years.

Perhaps you can clear it up for me, Doyle?