I'm not sure how Jesse James acquired the name Howard. i've researched Jesse and Frank about forty years.I find that a Thomas Howard lived in St Joseph even after Jesse supposed death in 1882. I also found a man who is said to be one of his twin son's who is said to have died in Tennessee and was buried on the Link Farm there. Apparently he didn't die there but was alive and well many years later.
See message # 42811 on the James family Forum. He was George Robert [Montgomery K.] Howard [James.] born Feb. 1st, 1878, Waverly, Benton Co. Tn. died: 14th March, 1940,Portland,Multnoma, Oregon.
Using the name George Howard he had three wives. he married Grace Butler. then Belle Lee, and #3 was Delaney Elizabeth Shaffer. not sure of exact order. He lived with Jesse's sister Susan and her husband Allen Parmer. Mo., Texas., Ark. He lived in Oregan, St Josaeph Mo.
Be sure to look at message # 42811 on the James family Forum [Genforum]. Lou Kilkgore.