Again, I do not necessarily disagree with your post. But,it does not, I believe, really answer Lincolns argument that, which he draws from the DoI, that the Union that created the AOC was the same Union that created the Constitution.Sorry for taking so long to respond OC.
I believe I have addressed the point of the OP. The Union has existed since 1774, but while it has consisted of one continuous union on a basic level, it has consisted of a number of fundamentally different, specific unions. As I see it the Framers recognized this dual nature of the Union, and therefore referred to the Constitution as a “consolidation of our Union,” while at the same time referring to it as the formation of “a more perfect Union,” meaning a new union. That may not be as neat and clean as some would like, but it's how they saw it. Two unions (actually more than two over that time period, perhaps four) AND one union.
Political science recognizes that states in a confederation remain perfectly sovereign, that sovereignty is legally supreme, and that secession from a traditional confederation is therefore not illegal. These concepts are supported by Vattel’s The Law of Nations, Article II and other aspects of the AoCs, Washington’s statements re: indissoluble Union, statements made in the Constitutional Convention (particularly by Morris on May 30), the Convention’s official letter, Madison’s explanation for dissolving the AoCs by less than unanimous consent (which shares much in common with secessionist compact theory), and the distinction Jackson drew between a league (traditional confederation) and nation (the more perfect Union) in 1832. Add to the list one highly respected constitutional scholar:
“Given the clarity of the Confederation’s foundational premise of state sovereignty, its classic international architecture, and its self-description as a ‘league,’ how could so many Americans in ensuing eras–Lincoln most famously–have denied that individual states were sovereign prior to 1787? Partly by mistakenly reading later history back into an earlier period. The Constitution itself set a trap for the unwary by using old legal words in new legal ways without clear warning. Just as the word ‘Congress’ under the Constitution described a different and more powerful institution than did the word ‘Congress’ under the Articles, so the phrase ‘United States’ in the Constitution meant something different and much stronger than did the same syllables in the earlier document. It is only a happy coincidence that the same thirteen ‘United States’ from the Declaration and the Articles became the first thirteen ‘United States’ in the Constitution. We must remember that when George Washington took office, North Carolina and Rhode Island were not part of the ‘United States’ as the Constitution used the term. Thus the Preamble spoke precisely of its purpose to ‘form’ a new–more perfect–union rather than simply ‘continue’ or ‘improve’ the old union.” – Akhil Reed Amar, America’s Constitution, A Biography, p. 27
Confusion originates from the fact that the Framers had invented the first federation, a union of states that form a nation rather than a league, the key characteristic being that sovereignty is divided between the union itself and the individual member states rather than being entirely held by the member states. The meaning of words like federal, national, state, and congress thereby changed markedly, as far as sovereignty and government power were concerned, just like the Union (continuity version) itself. And because the Framers and federalists were approaching it from a purely practical rather than theoretical standpoint, they didn't even bother coming up with a name for the new system of government/polity. They continued to call it a confederation for many decades, so that word took on a dual meaning as well. Rather than saying 'it's a federation' (a term eventually coined by political scientists, after the experiment had apparently succeeded), people like Madison had to go into a paragraph-long paragraph of this new type of union/confederation/political system. Furthermore, even before the Constitution two very different meanings of the word “compact” also applied, a fact secessionists would later try to take advantage of. The AoCs were a treaty, a compact among sovereign nation-states, but the Constitution represents a social compact, an agreement among individuals to form a political society (nation-state).
In addition, sovereignty is a legal concept. The concept on which western nations based their legitimacy. It doesn’t matter that the states were, as a matter of fact, dependent on each other to win and maintain their “independence.” The way THEY chose to legally define themselves was as 13 sovereign states (nation-states). That was their de jure status, no matter what their de facto condition was. As a matter of political science, then and now, a treaty of confederation does not change their legal status as 13 sovereign nation-states. Not that there are any more confederation; the are preeminently less efficient and effective than federations.
That there may have been more or fewer states in the Union after its creation by the DoI would be, to Lincoln, irrelevant, i.e.f the original States proclaimed in the DoI, is the same Union of 50 states of today.
It is entirely possible that the Union that declared its independence in the DoI could have included Canada, if Benedict Arnolds, eta. al., invasions of Canada had been successful. If the Treaty of Paris had returned the Canadian Provinces to England, Lincoln would probably have argued that the Union that signed the treaty was the same Union that authorized the DoI and, formation of both the AOC and Constitution.