Debra,

I have included a link regarding the battle of Griswaldville in Jones Co., Ga. It will answer some of your questions about the 11th Georgia Militia. While it does not mention the three brigades involved specifically, I am aware that the 11th was there through other documents. Perhaps this will be of some help.
http://ftp.rootsweb.com/pub/usgenweb/ga/jones/military/griswold.txt

Also, this Schley County pension application contains testimony that places Co. K of the 11th Georgia Militia at the Battle of Griswaldville. It also places Robert Burton at this battle and describes the seriousness of the scene.
http://ftp.rootsweb.com/pub/usgenweb/ga/schley/military/civilwar/pensions/mt198ucok11thr.txt

I hope this will be of a little help.

Harris