[You] Not in the way you seem to think they were.
Well, chief, since they were intact in their sovereignty under the Articles and there can be no doubt of that, then perhaps you'd better explain how, in your, Harry Jaffa's, and Lincoln the Conqueror's opinion, they were not sovereign when the Constitution was presented to them for ratification.
What you can't get around is that the bodies that sat down to deliberate ratification were the People in convention, and sovereign in every way that matters, under God and the sun.
You can't stand that, can you? And no wonder -- neither can your theory.
But they weren't, despite your misinterpretation of Article 2 of the AoC&PU. There were certain sovereign powers that were denied to the states in that document. If the states are denied the sovereign powers of making war or peace, contracting treaties with other sovereign entities, etc., then they cannot claim the full range of sovereign powers. Art. 2 is made in reference to their "internal" sovereignty - that is to say, other states could not interfere in their own internal affairs.
Were they sovereign, in the accepted sense of the term? A sovereign state exercises complete control over its territory and its actions. Did states? Could they carry on relations with other sovereign nations and states? No. Could they acquire territory or expand their influence? No. Could they raise armies, coin money, set their trade policies? No, no, and no. Could they decide their own form of government? Hell, no. The Constitution allows the states to run things within their own borders, within the restrictions and controls placed on them. They could no more unilaterally leave the Union than they could unilaterally join.
You can't stand that, can you? And no wonder -- neither can your theory.
I can stand it very well. I love a good laugh, and I get one every time you go off on one of your crazy sovereignty kicks