Kirby the answer to your question lies in the history of AI Baker. Baker in 1861 was leading a group of bushwackers formed on the Bluff and Rock Creeks of Lyon County. O.F. O'Dell 1st person reports Leander (Lee) Griffin, William Reed, Bill and Jim Anderson, Richard Pinson, and a man named John Ratcliffe were all members. They apparently terrorized farmers on the Kansas - Missouri line and did relatively well. Baker at the time was in significant financial duress and was trying to fund his way out of debt and back into politics by late 1861 and was functionally bankrupt by Oct 1861.

Griffin and Reed were cousins to Bill and Jim.

See:
O. F. O'Dell, "Along the Santa Fe Trail, And the Parts Respectively
Played by 'Jim and 'Bill' Anderson, and Members of their Infamous
Gang, in the Early 60's," Border Ruffian Troubles in Kansas (Lyndon:
L. D. Bailey, 1899), p. 48.
https://archive.org/details/fl-2194038-tn-2221116

And
L. D. Bailey, "Along The Santa Fe Trail, Bill Anderson his Gang,
And the Killing of Judge Baker, of Lyon County," Early Day's In Kansas
(Olathe: Charles R. Green, 1912), p. 26.
https://archive.org/details/earlydaysinkansa03gree/page/28/mode/2up?q=anderson

Ratcliffe had written to AI Baker that he had stolen horses from Samual N Woods an arch enemy of AI Baker who Baker had essentially run out of business and town eventually buying Woods newspaper due to local politics. Ratcliffe was writing to Baker as a pro-slavery man. Baker had swung around every point of the compass but as a slave owner prior to 1857 had been active with the pro slavery party in Kansas moving to the Free-State party when it became politically expedient.

see: Emporia News, Dec 7 1861.

If you remember Baker and gang were captured by a unit of the 6th Kansas Cav. and Baker was arrested and held at Ft Scott. No charges were preferred and he was released, supposedly due to the influence of James Lane. Baker had long been a fan and political supporter of Lane. Baker had formed a "Home Guard" unit in Council Bluffs (perhaps including most of the "gang") of 50 men or so and had attempted to get a commission early in 1860 and was rebuffed. The unstated here is was Baker running one of Lane's "boarder ruffian" units. In essence being a mercenary motivated by his dire economic condition.

So to get to your question, all the players were together and playing rough in 1861. Baker led, then Griffin with Reed as probably number 2 after the demise of Baker?

In any case Baker's hearing at the military commission was held March 24, 1862 and he appears back in Lyon county by April 9. In a letter to the Emporia News April 12 1862 edition he indicates he had settled a claim for several thousands with the government and started to date Bill and Jim's sister. Further he had nothing but good words for WC Anderson. Baker had once referred to Anderson as his "esteemed friend, whose pleasant family know how to entertain their friends." See: Council Grove Press, June 22, 1861. So there is lots of track record between the Anderson's and Baker. It was the dissolution of the engagement of Mary Anderson to Baker that led WC Anderson to Baker's house and subsequent murder of Anderson. Lee Griffin supposedly stole horses from Ira Segur, father of Annis Segur betrothed to Baker. So clearly they were all together through trying times before landing back in Missouri. O.F. Odell's store at Allen KS (142 mile creek) was robbed by Anderson and company after the Baker murder as they were making their way east on the Santa Fe Trail.

The Yaeger/Anderson raid in May 1863 culminated in failure to capture the government train but the group stopped at Jennerson's store and burned him out and killed a soldier of the 11th Kansas on furlough by the name of Strieler. This was a strike down the Santa Fe Trail and was right in the middle of Griffin, Reed and Anderson's stomping grounds. Yaeger may have been along and "in charge" due to having Quantrill's trust and the other boys from Kansas were new to Quantrill.

Leander Griffin is found in the 1860 Census in Ridgeway, Osage, Kansas Territory, Post Office Burlingame with 2 brothers, in the housedhold of Medora (nee Rice) Houge/Hoge. Husband Mitchel Houge was in the Kansas 9th Cav. Her mother was Mary Griffin married to Hollem Rice. 1850 finds the Rice household with Houge in Iowa, neighbors to Anderson's and Bakers. Hogue and Margaret Medora Rice marry in 1852 in Cooper County MO. Mary Griffin Rice married Hollem Rice in St Charles MO 1833. Through this connection we find the will of Sinclair Griffin in Van Buren Iowa that lists Eliza Ann as his wife, daughters, Sarah Anderson and Mary Rice. Sons listed include William Kirk Griffin, Leander Sinclair Griffin, George Francis Griffin, and Stephen Best Griffin. Leander was born abt 1833 making him 27 in 1860. His father Sinclair was a vet of 1812 and left his rifle to Leander in his will. How Sarah Griffin Anderson fits is still a mystery but is no doubt the source of Lee Griffin being a "cousin" of Bill Anderson. In 1849 William Kirk is appointed guardian of Leander in Van Buren Iowa. Leander would have been 16 at the time. What happens to him after the Baker murder is not clear though there is a suggestion that he may have been killed on Anderson's raid on Tillotson's Store near Olathe KS in August of 1862.

To further round out that this the right gentleman from: The Weekly News-Democrat, July 12, 1862, Page 2. via Newspapers.com (https://www.newspapers.com/article/the-weekly-news-democrat-a-i-baker/111662675/ : accessed August 11, 2024), we find:

"At Elm creek they fired into the house of a Mr. Jacoby, who had taken some part in getting them arrested. It was their intention to have killed this gentleman, but a Santa Fe train which was encamped near Jacoby 's residence saved his life. At the next station they stole two more horses, belonging to the Kansas City and Council Grove Stage Company. From this place they proceeded on down the road, avoiding Burlingame, and threatened, to a gentleman near that place, that if the people of that village disturbed the property of Hollam Rice who, as those who have traveled the road between here and Lawrence will recollect, kept a kind of stopping-place at Dragoon creek, near Burlingame, and who lately left for Iowa because of his supposed complicity with this band of horse thieves they would lay that town in ashes."

Then we have this note that teases the mind to dig deeper:
The Weekly Gazette, October 10, 1863, Page 2. via Newspapers.com (https://www.newspapers.com/article/the-weekly-gazette-william-griffith-one/22534537/ : accessed August 11, 2024),

"The Sure Footsteps of Justice. At the last term of the District Court in Linn county, Kansas, a man named Griffith or Griffin, one of he fiends who under the lead of Hamilton, went over from Missouri into Kansas, in the summer of 1858 and collecting up from their fields and homes, eleven, unarmed ,men marched them into a ravine and shot them down in cold blooded massacre known in history as, the "Maria des Cygnes Massacre" was tried and convicted of tbe murders then and there committed.

He was sentenced, by Judge Thatcher to be hung on the 30th day of October instant.Thus, after the lapse of more than five years, the sure footsteps of justice, have overtaken one of. the participators in that horrible transaction. A singular feature of the case is that the criminal was arrested by old Mr. Hairgrove, one of the, men who was shot down at the time of the massacre, but who recovered from his wounds."

Does anybody know who the principals of this depredation in 1958 was besides Hamilton?

Enough contemporaneous folks call Reed, William Reed I can't help but believe the name is correct. O'Dell and Baily both refer to him as William. I still don't have a good handle on him either in Kansas, Missouri, or Iowa.

JJR