Here were the authorized powers of the South Carolina Commissioners:
WASHINGTON, 28th DECEMBER, 1860.
Sir: We have the honor to transmit to you a copy of the full powers from the Convention of the People of South Carolina, under which we are "authorized and empowered to treat with the Government of the United States for the delivery of the forts, magazines, light houses and other real estate, with their appurtenances, within the limits of South Carolina, and also for an apportionment of the public debt and for a division of all other property held by the Government of the United States as agent of the confederated States, of which South Carolina was recently a member; and generally to negotiate as to all other measures and arrangements proper to be made and adopted in the existing relation of the parties, and for the continuance of peace and amity between this commonwealth and the Government at Washington."
Jefferson Davis sent three Confederate Commissioners to Washington to negotiate with President Lincoln. Lincoln would not meet with them. The Confederate Commissioners dealt with Seward, Lincoln's Secretary of State, through an intermediary. Here are the instructions of the Confederate Commissioners authorized by the Confederate Congress:
That said commissioners be further instructed to present to the Government of the United States assurances of the sincere wish on the part of this Government to preserve the most friendly relations between the two Governments and the States comprising the same, and to settle, by peaceful negotiations all matters connected with the public property and the indebtedness of the Government of the United States existing before the withdrawal of any of the States of this Confederacy; and to this end said commissioners are hereby fully empowered to negotiate with the Government of the United States in reference to said matters, and to adjust the same upon principles of justice, equality, and right.
Ping to post 21 Link.
Of course one way to maintain most friendly relations would be to not interfere with unarmed supply ships and not to fire on US forts, not to steal US cannon, etc.