Thanks to Bryan Howerton for his response to my question in the thread below regarding Major Black and the 23rd Arkansas. Rather than hijacking that specific thread, I thought perhaps it better to start a new one regarding my particular issues with the 12th Arkansas, and to a certain extent, the 11th and 15th Arkansas infantry regiments.

As to Bryan's informative response to my confusion:

OK, maybe I'm beginning to understand--somewhat. The bulk of the 12th Arkansas was captured at Island #10 and sent to prison with the other captured regiments from that post. At the prison camps, they joined with those regiments previously captured at Ft Donelson.

As was the case with other regiments, there were escapees from the surrender, including those in hospital or on detached duty, etc. Those of the 12th Ark were consolidated into two companies and assigned to the 6th Arkansas until after the 12th Arkansas was released and reorganized. Meanwhile, the 6th Arkansas embarked on Bragg's Kentucky campaign, and thus, these two companies were unable to actually rejoin the exchanged regiment until about December, as was the case with other such escapees that had been attached to regiments with Bragg.

And, specifically for the captured Arkansas regiments, other escapees returned to Arkansas where many were shanghaied by Hindman and placed in his new regiments being organized there.

Finally, there are those of the 12th Arkansas [surely, there could not have been many of this regiment after accounting for all the others disposed as mentioned.] that Bryan indicates were consolidated with the 14th and 23rd Arkansas regiments on Sept.10th at Saltillo, MS, to form the 12th/14th/23rd Arkansas consolidated regiment.

Apparently, this consolidation lasted only a couple of weeks as it is not so indicated in Corinth battle reports.
“The Lost Account of the Battle of Corinth” would seem to show the 14th and 17th Arkansas regiments consolidated during that battle, but so far, I have not seen this mentioned in other sources.

Strangely, the 12th is not listed or named in orders as were most of the other returned POW regiments, as they went through a succession of brigade assignments and regimental consolidations. Also conspicuously absent from brigade assignments, regimental consolidations, orders or official correspondence [at least in the first weeks after reorganization] are the 11th and 15th Arkansas regiments. However, the 12th Arkansas disappears from the records much longer than these other two Arkansas regiments.

Prisoners of the 12th Arkansas were delivered to Vicksburg on or about Sept. 16, and/or Sept 23, 1862. The regiment was then reorganized by the election of new officers on Oct. 2, 1862 at Jackson, MS. These are similar dates for the several other released regiments.

As Bryan has previously posted-"Fay Hempstead, in his A Pictorial History of Arkansas [1890], says the 11th and 12th Arkansas regiments were consolidated after release. Hempstead didn't cite a reference for this temporary consolidation with the 11th Arkansas, and I've not seen anything else that alludes to it. "

I have found other sources that allude to this same initial consolidation of the 11th & 12th Arkansas regiments:

Tom Ezell's former web site featuring capsule histories of Arkansas regiments indicates---
"While Col. Gantt was confined as a prisoner at Fort Warren, the 12th Ark was exchanged & reorganized at Jackson. Col. Reid, Lt. Col. Ed Jordan, Maj Walker, Adjt Hemingway, QM Jonas were elected as the regimental officers in this 2nd reorganization. There were too few men to bring the regt up to effective strength, so the officers were granted leave to return to Arkansas to recruit replacements, while the enlisted men were temporarily attached to the 11th Ark under Col. Logan. When the officers returned to the regt, the added recruits brought the regt's strength up to approximately 500 men in the ranks. The co officers in this new organization were: Co. A, Cpt. Stewart; Co. B, Cpt Donnell; Co. C, Cpt. Johnson; Co. D, Cpt. Linzee; Co. E, Cpt.Glasgow, Co. F, Cpt.Bowen; Co. G, Cpt. Doggett; Co. H, Cpt. J.E. Inge; Co. I, Cpt.Archer; Co. K, Cpt.Davis"

And from Arkansas CMH -p. 596. "11th Arkansas exchanged Oct and consolidated with the 12th Arkansas"

I have also seen pencilled notes at NARA-that make reference to a variation on this consolidation: Late Sept-Oct-11/12/17 Ark consolidated from MR source. I presume MR means muster roll

NARA-12th Ark-Field officers elected at reorganization of Oct 2, 1862, at Jackson, were Colonel Reed [formerly Major], Johnson, Walker

The new regiment, when reorganized, only contained about 200 men, so the field officers were sent to Ark to recruit, while the line officers & men were sent to Port Hudson, & temporarily consolidated with the 11 Ark, Col Logan, in Gen Beall’s Brigade.
[I seemed to have temporarily lost track of the citation for this statement, it being jumbled together with my other mass of notes.]

"Ark Confederates in the Western Theater"-Willis p. 282
Oct. 20th, 1862 letter of man in 9th Ark refers to 2 brothers camped nearby [Holly Springs]. The footnote says the brothers were in the 12th Ark and had been captured at Island 10 and exchanged in September in time to fight at Corinth.-but no source is given for this statement regarding being exchanged in time to fight at Corinth. None of the other several exchanged regiments arrived in time to fight at Corinth.

As with a comparatively few other recently released regiments, the 12th Arkansas shows a later "exchange" date of Nov. 10, 1862. Perhaps this is another reason for being omitted from the records, after reorganization.

Perhaps their "later" exchange date was in response to:
10/21 Gen Van Dorn, Cmdg. Holly Springs. from Pemberton : The Lt Gen cmdg. directs me to say that by instructions from the War Depart, Gen Tilghman will retain 2,000 of the returned prisoners, as the terms of the exchange are not fully completed.NARA

11/22/62 The earliest references to individuals [not the regiment] of the12th Arkansas is a request for discharge from a soldier in the 12th Ark--forwarded to Beall at Port Hudson [for him to handle].

12/14/62 And, then an entry in Post Hospital Ledger at Port Hudson for a man in the 12th Arkansas.

Finally, apparently the first official post-prison reference for the 12th Arkansas is in a table of organization [from The Official Records] for March 31, 1863; over 6 months after arriving at Vicksburg from prison!

I’m not ready to give up–-yet, but, I would appreciate any help in digging up seemingly scarce information on the 12th Arkansas during the first few months after its release from prison.