Hold on, there! Common practice? What historical precedents would there have been for what you are suggesting happened here? These people were ratifying a Constitution, not haggling over a used car.
Article VII of the Constitution provided state ratifying conventions with the option to ratify the Constitution as written. And each of the states did ratify the Constitution as written.
Do you see the term "counter-offer" in any of the states' ratification documents? Did you know how hard Mr. Madison worked to make sure that the state conventions framed their ratification proposals for bills of rights as "recommendations" rather than qualifications?
And in the first Congress, Madison worked tirelessly craft and pass a Bill of Rights to address the recommendations that the states made even though he felt personally the BoR was not necessary and could possible be dangerous. He did not accomplishing all that they asked for, (New York had a list of about 20 recommendations, including term limits on the President) but he accomplished enough that no state complained.
Did they invent some new legal system just for the Constitution? Where is it written in the Constitution that non-traditional methods were to be employed?
Article VII of the Constitution provided state ratifying conventions with the option to ratify the Constitution as written. And each of the states did ratify the Constitution as written.
The Ratification of the Conventions of nine States, shall be sufficient for the Establishment of this Constitution between the States so ratifying the Same.It does? Where?
"Do by these Presents".
The only reason this looks relevant at all to the secession debate is because the rebs still deny the distinction between revolution and secession.