How can someone reclassify while still in AIT?

if he gets the opportunity to reclass they're usually given 3 options from whatever the needs of the army is at the time. (they're not usually top of the line jobs). However, he will not get to know what those options are until he's officially failed from his AIT. Which means if he doesn't like the options then thats too bad, he has to choose one.

56M is a pretty cool job, unless theres something about it that he really can't stand, then I'd suggest sticking to it. Now AIT's suck, no matter what job they are. Are you sure he doesn't want the job? Or maybe he's just complaining because hes in tradoc.

Pretty sure the only way for him to change his MOS now would be to flunk out of his current AIT, which would then mean he'd end up as "needs of the Army" and end up in one of those "more worst" combat arms jobs. Your brother signed a contract, he's going to be expected to uphold his end of it.

Brother, I know you asked about a year ago, but answers from "ranking" Brothers not withstanding aren't totally correct.
I gained my secondary MOS via OJT.
I was assigned to Ft. Belvior as an instructor (52C Gas Turbine Generator Specialist), but they had too many and I got asked to handle supply and distribution for the course, aka a USPS driver (complete with a Top Secret Clearance, as I carried Orders and other Personnel files). After a year, I requested the Secondary MOS, but didn't stay precise. I wanted a Courier MOS, but got 64C10...
In other words, ask - the worst they can say is "No!".

Suck it up and drive on... no way you can reclassify,

You cannot reclas in AIT!

As a 56M, his AIT is easy. Tell him to push through, get stationed and start doing the job he signed up for. As a 56M he will have the rare chance to see what most MOS' are like when he conducts ministry support with different units. I would highly suggest he check out other MOS options through the eyes of other soldiers before he is given the green light from his command to change MOS'. Also tell him to stay physically fit, thats really the only thing that can keep him from progressing to another MOS.

Do his contract then when his re enlistment becomes available reclass then lol that’s about his only option

The only other way is if the solider in AIT somehow no longer has the prerequisites. For instance a 92R Parachute Rigger does not pass Airborne school. Someone in a Military Intelligence MOS could not pass the background check for the necessary clearance.

Has he spoken with his company commander about reclassification of his MOS?

For one AIT is nothing like doing your actual job. I was no where near a chaplain assistant but all the ones I know how a pretty sweet gig sitting at Squadron HQ. I’d tell him try it out once he gets to his duty station do his initial enlistment and if he doesn’t enjoy it then start off of an MOS he would like then go from there. He can always re-enlist for another MOS after time requirements are met.

He cannot reclass. He could fail out (which is horrible recommendation) and then he would go before some type of Academic Deficiency Panel where they would make a determination of recycling him to a different class, reclass, or kicking him out. I would say he needs to figure his life out and talk to his unit's MFLC (Military & Family Life Counselor) or maybe a Chaplain and get some good counseling to help him sort out these emotions and make a determination on if he truly doesn't want this job or if there is something else going on that is a temporary issue that can be addressed to alleviate his frustrations and allow him see that its not as bad as he currently believes it to be.

Through my years of Active Duty, I've either known, observed, or had Chaplains Assistants as my Soldiers. In garrison, they are basically the Executive Assistant and "Chief of Staff" for the Chaplain. That means the Chaplain's Assistant manages the Chaplain's schedule, controls access to the Chaplain, manages religious programs, etc. Chaplain's Assistants also prepare religious services, control religious service accessories, the chapel, etc. It keeps one busy, but is hardly a "sucky" job.

Deployed, Chaplain's Assistants do all the garrison stuff, but are also the Chaplain's bodyguards, as Chaplains are not allowed, by Geneva Convention, to be armed. So 56Ms are "combat" personnel downrange.

I have known several Army Chaplains, and they have all been really great people to know, to be around, and have access to. One in particular for whom I have enormous respect and awe, is a former police SWAT officer, as well as a former Navy Sailor.

Tell your brother that AIT sucks, no matter what the MOS. It will get better once he graduates and gets to his first duty station. He may even come to like his job. If he doesn't, well he can reclass to a MOS that he feels he may like better at the end of his enlistment. There is also a voluntary reclass request, but he has to be in his current MOS for a certain amount of time (1 year seems to come to mind, but it could be different). But that's another whole discussion.

I don't believe you can just reclassify after while in AIT unless you fail AIT and I don't believe it is guaranteed.