Hoping someone can help me clear up another point of confusion regarding my great grandfather's service in the 21st Alabama Infantry:
William McDaniel Reaves, Wilcox County, Alabama, Private, Company F, 21st Alabama Infantry, enlisted February 26, 1863 at C. Bluff, captured at Fort Gaines August 8, 1864, received at Ship Island, Mississippi, from New Orleans. La., October 25, 1864, exchanged January 4, 1865. Following his return to service, McDaniel Reaves received his parole with other members of his command at Meridian MS, May 13, 1865.

Where I am confused is related to the what happened to him when he was released from Ship Island. My confusion is similar to the post I saw from Alan Pitts on 5/31 detailing the difference between being paroled, exchanged and taking the oath of allegiance. Since I know my GGr was paroled from Meridian in May 1865, it seems likely that was a result of him returning to the 21st Alabama and subsequently being captured with the fall of Fort Blakely in April 1865. I read in the Scriber book on Ship Island (Rosters and History of the Civil War Prison Ship Island, Mississippi) that the men captured at Blakely (many former prisoners of Ship Island) were returned to Ship island for a brief time before being sent to Vicksburg and then to Meridian where they were paroled and took the oath of allegiance. In that book, the path to Vicksburg from Blakely only went through Ship Island so I am looking for confirmation that my GGr might have spent two stints as a POW at Ship Island. But, if that is the case, why would his service record not have indicated that (I have never seen it in any information I received on his record). So, I am trying to get confirmation that the following is accurate (found from several sources that I have tried to put together):
1. Men released from Ship Island in Jan 1895 were exchanged, not paroled and did not necessarily take oath of allegiance
2. My GGr returned to his unit (21st Alabama Infantry) that was subsequently fighting at Blakely and was captured with the surrender in March 1865
3. Seems he may have been returned to Ship Island Prison for 2 months, then sent through New Orleans to Vicksburg, where he was paroled and took oath of allegiance.

If #3 above is not true, or verifiable, how else would he have been sent to Vicksburg? Is there any other record of the men from Blakely getting to Vicksburg?

Hope the question makes sense ad soemone can help me with the details. Thank you, as always!