[rockrr]

The South had the right to secede.

Right. But not unilaterally and not willy-nilly. Of course you're speaking hypothetically because no state has yet done so successfully.

The Declaration of Indpendence decribes the states as: “Free and Independent, they have full Power to levy war and to do all other Acts and Things which Independent States, may of right do.”

Those powers were assigned to Congress in the United States Constitution Article 8.

[ConservativeNewYorker]

So either they had a right to secede or they didnt. Why should South Carolina need New Jersey to agree to allow them to leave?