I have never heard that there were changes in personel whe Ga. state troops went to VA. Below is the story of the creation of teh 18th Ga. My Great Grand Father, Lemuel H. Boring, and two great uncles, Alexander and Francis,were in Co. A, from Cobb County. Their service records show them as enlisting in April, 1861. Lemuel died at Seven Pines. Francis was wounded at Spottsylvania, and capturedin Roswell, Ga., whie on recuperative leave. He was sent to Camp Douglas. Alexander was captured at Cedar Creek, Ocrober 19, 1864. He was sent to Fort Delaware. They both were paroled in June of '65. Stan

"As a result of a call to arms by the Georgia state legislature and Governor Brown, Colonel William Tatum Wofford, along with his second in command -- Major J. Johnson and Adjutant John Griffin, raised a confederate regiment in Cass County, Ga. on April 10, 1861. (Cass County was located just northwest of Atlanta. Today it is known as Bartow County, named after General Francis Bartow who had died at the Battle of First Manassas.)
On April 22nd, the newly formed regiment was assigned as the First Regiment, Fourth Brigade, Georgia State Volunteers and soon after posted to Camp McDonald at Big Shanty, Georgia, now known as Kennesaw, Ga. for training. The regiment consisted of ten companies, the Ackworth Infantry; Newton Rifles; Jackson County Volunteers; Davis Invincibles; Stephens Infantry; Davis Guards; Lewis Volunteers; Rowland Highlanders; Dooly Light Infantry; and the Rowland Infantry.

On July 31, 1861, a public "Grand Review" of the brigade was held in Big Shanty, Ga. Citizens of Marietta and the surrounding communities came to admire the newly trained troops, as they prepared for their departure to Richmond, Virginia. They departed on August 3, 1861 and arrived in Richmond on August 9, 1861. Here, they were mustered into the Army of the Confederate States of America and redesignated as the 18th Georgia Regiment of Volunteer Infantry."