As you say, the footnote details a second proposition, that the Fugitive slave law should be amended by granting a jury trial to the fugitive, which was rejected. And a third proposition, that Congress should recommend that the states revise legislation concerning persons recently resident in the state and repeal all in conflict with the constitution, that was also rejected. But what makes me think that the proposals were Seward's is that the footnote continues, "Whereupon the Republican members of the committee, together with Trumbull and Fessenden, met to consider Lincoln's resolutions..." If the proposals listed above were Lincoln's then why meet to consider them again when they had already been voted on? I think it's an indication that the proposals for the amendment and other two originated with someone other than Lincoln, probably Seward. And that Lincoln's three proposals were the ones listed in his letter to the Committee of Thirteen, none of which called for an amendment protecting slavery.
Right, Seward was on a tear, doing his typical moderate-Republican thing, wheeling & dealing trying to craft a "compromise" with Democrats to save the Union.
In the mean time, president-elect Lincoln, before his inauguration, held back, kept silent on most issues and merely insisted that the Republican position on slavery in the territories would not be compromised.
Evidence that Lincoln interfered with, or even, ahem, "colluded" with Seward is minimal to non-existent.
In the mean time Lincoln-Republicans in Congress stood fast in opposition.
So we can say that Ohio Republican Corwin's amendment grew out of efforts by Mississippi Democrat Senator Jefferson Davis to mollify Southern fears of Lincoln's Black Republicans, before his own state seceded, the amendment was supported by Democrats in Congress, steered by Republican Senator Seward, passed over Republican opposition and signed by Democrat President Buchanan.
Evidence of Lincoln's role, if any, is lacking.
Seward's freelance wheeler-dealing did not end with Lincoln's inauguration on March 4, 1861, but continued throughout the Fort Sumter crisis.
Sorry for the long delay in replying. I have been fighting flu and subsequent bronchitis for four weeks now. Every now and then I’d think I was getting well, only to have the constant coughing return. I’m getting better now by taking amoxcillin.
I think a little context is necessary here. Lincoln offered the Secretary of State post to Seward on December 13, 1860. Seward accepted it on December 28. On December 16, Seward wrote Lincoln that Weed was going to come talk with Lincoln and that he, Seward, would talk with Weed before the trip and talk with Weed after he returned from Springfield, which Seward did.
Here is Seward's Dec 26, 1861 letter to Lincoln describing what happened, only part of which was summarized in your link. You can find Seward’s letter at Nicolay and Hay's book, Abraham Lincoln: A History, Volume 3, page 262. [Link]. From the letter (my bold below):
I had only the opportunity for conferring with Mr. Weed which was afforded by our journeying together on the railroad from Syracuse to Albany.
He gave me verbally the substance of the suggestion you prepared for he consideration of the Republican members, but not the written proposition. This morning I received the latter from him, and also information for the first time of your expectation that I would write you concerning the temper of the parties and public here.
I met on Monday my Republican associates on the Committee of Thirteen, and afterwards the whole Committee. With the unanimous consent of our section I offered three propositions that seemed to me to cover the ground of the suggestion made by you through Mr. Weed as I understood it.
First. That the constitution should never be altered so as to authorize Congress to abolish or interfere with slavery in the States. This was accepted."
Second. That the Fugitive slave law should be amended by granting a jury trial to the fugitive. . . . '' This in opposition to our votes was amended so as to give the jury in the State from which the fugitive fled, and so amended was voted down by our own votes. The Committee had already agreed to Mr. Crittenden’s amendment concerning the fees of the commissioner, making them the same when the fugitive is returned to slavery as when he is discharged.
Our Third resolution was that Congress recommend to all the States to revise their legislation concerning persons recently resident in other States, and to repeal all such laws which contravene the Constitution of the United States, or any law of Congress passed in pursuance thereof. This was rejected by the pro-slavery vote of the Committee.
To-day we have had another meeting. I offered, with the concurrence of my political associates, a fourth proposition, viz.: That Congress should pass a law to punish invasions of our States and conspiracies to effect such invasions, but the latter only in the State and district where the acts of such complicity were committed. This by the votes of our opponents was amended so as practically to carry out Mr. Douglas’s suggestion of last winter for the revival of the old Sedition law of John Adams’s time, and then was rejected by our own votes.
The first and fourth propositions discussed above were basically consistent with the 1860 Republican platform, that I imagine Lincoln ran on. Here is Item 4 of the platform:
4. That the maintenance inviolate of the rights of the states, and especially the right of each state, to order and control its own domestic institutions according to its own judgment exclusively, is essential to that balance of power on which the perfection and endurance of our political fabric depends, and we denounce the lawless invasion by armed force of the soil of any state or territory, no matter under what pretext, as among the gravest of crimes.
The first proposition above that the Committee of Thirteen considered was rephrased from that of the platform to address slavery specifically and to say essentially that the Constitution should not be altered (i.e., amended) to authorize Congress to abolish or interfere with slavery in the States. Republican Representative Corwin later achieved the goal of the first proposition through the Corwin Amendment.
Interestingly, the first proposition got the votes of all the Republican members of the Committee of Thirteen and all but two of the Democrat members. The Democrat members of the Committee of Thirteen were often the ones who voted against the Republican propositions presented to them. The Democrat members included Powell, Hunter, Toombs, Douglas, Davis, Bigler, and Rice.
In his first inaugural speech Lincoln addresses slavery and, in fact, quotes Item 4 of the Republican platform that I listed above:
I have no purpose, directly or indirectly, to interfere with the institution of slavery in the States where it exists. I believe I have no lawful right to do so, and I have no inclination to do so.
Those who nominated and elected me did so with full knowledge that I had made this and many similar declarations and had never recanted them; and more than this, they placed in the platform for my acceptance, and as a law to themselves and to me, the clear and emphatic resolution which I now read:
Resolved, That the maintenance inviolate of the rights of the States, and especially the right of each State to order and control its own domestic institutions according to its own judgment exclusively, is essential to that balance of power on which the perfection and endurance of our political fabric depend; and we denounce the lawless invasion by armed force of the soil of any State or Territory, no matter what pretext, as among the gravest of crimes.
You are correct that the written propositions that Lincoln gave Weed were discussed later with the Republican members of the Committee according to Seward’s letter to Lincoln. The Republican members decided not to offer Lincoln’s written proposals to the full Committee:
This evening the Republican members of the Committee with Judge Trumbull and Mr. Fessenden met at my house to consider your written suggestion and determine whether it shall be offered. While we think the ground has already been covered [rb: by the four propositions above and the discussions relative to them, I think] we find that in the form you give it, it would divide our friends not only in the Committee but in Congress; a portion being unwilling to give up their old opinion that the duty of executing the constitutional provisions concerning fugitives from service belongs to the States, and not at all to Congress. But we shall confer --- and act wisely as we can.''