Oh...so they DID consider it, huh? Gee...that's just what I was saying...
In other words, the moderates prevailed, and it was decided to issue the declaration first in an attempt to get concessions, but secession was the option if they didn't.
I'm still waiting to see these proceedings of the secret meetings that you've found. From what I have read, there were no records of the proceedings, only the Report and Resolutions, and general descriptions of what had occurred.
...but there was no delegation making demands of the Administration and there were no threats made to secede. And if you have any evidence to the contrary then by all means bring it out.
Another strawman. It has already been pointed out that the threat to secede was pre-empted by the end of the war! However, if you want an account of the Massachusetts commissioners, here's an excerpt from the uncredited Hartford Convention Wikipedia entry:
Hartford Convention delegates were apparently in favor of New England's secession from the United States, and either forming an independent republic, or reuniting with Britain. No such resolution was adopted at the convention; however, Massachusetts actually sent three commissioners to Washington, D.C. to negotiate these terms. When they arrived in February, 1815, news of Andrew Jackson's success at the Battle of New Orleans, and the signing of the Treaty of Ghent, preceded them and, consequently, their presence in the capital seemed both ludicrous and subversive. They quickly returned to Massachusetts.
Found here .
"The meeting opened on December 15, 1814, and was held in secret. Though secession was debated, the action was rejected as premature. The convention did, however, issue a declaration, calling on the federal government to protect New England, and offering several amendments to the Constitution for review by Congress. The final report was issued on January 5, 1815. The amendments were read into the journals of both the U.S. House and the U.S. Senate, but no action was taken..."
Found here
I should also point out that nowhere does anything you posted support you claim that secession was discussed in Washington.