Richard,
George Todd commanded about 100 former Quantrill men and about 18 October requested permission to join many or most of them to the Confederate army as it passed westward through Lafayette County. It is my understanding from reading that most of them joined Brigadier General Joseph Orville Shelby's cavalry brigade, since a number of the guerrillas had been part of various of Shelby's regular and irregular units earlier in the war at different times. Confederate officers accepted the offer and placed Todd and a number of his men in the forward scouting sections, since a number of the guerrillas knew that area intimately. On 21 October George Todd himself was mortally wounded somewhere in Jackson County by a Union sniper's bullet, and his men buried him in the Independence graveyard at night. A problem developed when some of the former Quantrill men killed some Union POW's, as they were accustomed to fighting under "no quarter" rules, which were ordered in Missouri by Federal officials back in spring 1862, and that hateful rule had been in effect since then in Missouri. Union troops were incensed on discovering evidence of this murder on the battlefield (I seem to recall from my reading Yanks found some corpses of comrades with hands tied, but not sure) and killed some of the Confederate POW's in retaliation. This lead to terse messages exchanged between officers of the two sides leading General Price about October 23 or so to order all the guerrillas expelled from his army, which was later brought out in testimony at a Confederate Trans-Mississippi Department court martial, as described in the "Official Records."
Regarding some of Quantrill's former men riding with Colonel Sidney Drake Jackman, I have not read that. However, Jackman was a highly successful behind-Union-lines Confederate recruiter in the Boone and Howard County area during a number of months of 1863, and was held in high esteem by the guerrillas, similar to the high esteem they had for Shelby. Since the several bands of west-central Missouri guerrilla bands had several men from that part of Missouri riding with them in October, I can see how some of them would join Jackman's command at the time others were joining Shelby's ranks. I have not read of that, but I can easily see how that could have taken place.
I hope that helps, Richard.
Bruce Nichols