Some units, mine included, have been re-designated.
I assume, since I have not heard back from Fancy yet, this is to fall in line with Historical Unit Re-designations but ...
I can only speak about Cobb's Legion (GA) Infantry and Cavalry, as I have not researched the others, so here is what happened Historically ...
The Higher Command could not grasp the new and innovative Combined Arms concept so the Legion was disbanded AS A SINGLE UNIT before it saw it's first combat.
However, the individual units retained their Original Legion designation until 1864.
Even after they were re-designated 9th GA Cavalry the Officers and Troopers refused to be referred to as anything other than Cobb's Legion Cavalry.
The Infantry retained their original designation for the length of the war.
Per the National Park Service ...
"Cobb's Legion was organized by Howell Cobb during the spring of 1861 and soon moved to Virginia. The legion was composed of cavalry, infantry, and artillery, but did not serve as one command. The artillery company was an independent unit known as the Troup Light Artillery and its history is given under that name.
The cavalry battalion included men from Richmond, Fulton, and Dougherty counties and contained six companies. Later five more were added and the unit served with eleven until July, 1864.
At that time one company transferred to Phillips' Georgia Legion. Its strength now totaled 526 officers and men. Also its designation was changed to the 9th Georgia Cavalry, but was rarely used."
The Book Titled ...
Cobb's Legion Cavalry: A History and Roster of the Ninth Georgia Volunteers in the Civil War by Harriet Bey Mesic
contains a History, Final Disposition of it's Troopers and Biographies of the officers and the nearly 1500 men of the regiment.
There are numerous instances of the rancor and derision this re-designation caused and instances of Refusal to use the new Designation.
None of which occurred before 1864.
I hope this info helps.