The one thing worse than having someone else get credit for something that you know is yours, is that sick feeling you get when someone points out to you that something you thought was yours actually came from somewhere else. It is so easy to unconsciously plagiarize. And when your focus is on lyric rather than melody, as I believe was true for Mr. Dylan early on, you don't always realize that you borrowed/used/incorporated/stole the melody that fit the words so well.
One other thing that I think should be considered in this discussion is the nature of the music business back in the 60's. Bob Dylan the "singer/songwriter" probably finished the recording, tossed the lyric sheets to Albert Grossman who turned them over to a lawyer who filed the copywrite documents without ever questioning if anyone else should be credited. I doubt that too many people at that time, even true believers, would have imagined that someone 40 years later would be questioning the derivation of the melody line on Farewell Angelina. Although people should not be excused for things done in their name, I also don't think it's fair to assume that Dylan willfully took credit that he knew wasn't his. And at this late date, I doubt that he feels much of a need to correct the record. I'm glad that you guys are doing it, though. I was not aware of the specific derivations of some of these tunes and it's interesting to find out the truth.
As far as Lay Down That Weary Tune - there is a superficial similarity to the River is Wide, but I don't think they're the same song. Of course, I have been wrong before. . .