Thank you for your reply and for reminding me that the 7th Regiment was a volunteer unit and organized at the beginning of the war. That will be helpful because Mr. Martin's info from above makes sense, I just have to find documentation to back it up and dates of organization will help.
I was actually thinking about doing a history of the 7th Battalion (couldn't do the 7th Mississippi Volunteer Regiment cause you guys have already done such a good job on it) for my Senior Thesis/Project for the Honors College at USM. That's how the question regarding battalions and regiments came up.
But, I've actually had a change of plans and have picked another topic. Since it has yet to be approved, I'd rather not mention it now but I will probably need your help, if you don't mind, as it involves quite a few members of the 7th Regiment. Hopefully, it will be approved soon and I can't let everyone know.
If for some reason I'm unable to work on the new topic, I'll definitely do the 7th Batt'n, otherwise I'll have to save it for another thesis/degree at another time.