Interesting question. It's been awhile since I've read the Confederate Army rules and regulations, but as I recall, they state that an infantry company mustered into the regular Confederate States Army (CSA) shall consist of 100 enlisted men (privates, NCOs, musicians) and four officers (captain and three lieutenants). The section dealing with the Provisional Army of the Confederate States (PACS) -- which as you know were volunteers provided by the various States, and which constituted the majority of the Confederate army -- states that the volunteer companies shall have the same organization as the regulars, except that the President can limit the number of enlisted men to from 64 to 100 men per company.

I know that some States offered huge volunteer companies, well in excess of 100 men (Virginia and Georgia in particular come to mind) and that some of those companies were divided into two companies, each with somewhat less than 100 men. I presume that is why the regulations were amended to allow for companies of no less than 64 men on a case-by-case basis. That would seem to be the basis on which Hindman issued his order regarding Dawson's regiment.

Incidentally, cavalry companies were held to a different standard from the infantry. I cannot recall the exact number, but regular CSA cavalry companies, were supposed to consist of about 70 men and four officers.

I guess I should dig out my old copy of the rules and regulations and re-familiarize myself before I post things like "presume" and "about". Otherwise I'm not really helping anyone.