Two paths for veteran Union soldiers to continue serviing:

1) Some Union soldiers who were wounded bad enough to prevent them from marching and fighting, or had been too debilitated by illness to continue to perform combat duties, but who still wanted to serve, sometimes transferred to the Invalid Corps. As members of the IC performed nursing duties, guard duties etc. Their uniforms were a sky blue color to set them apart from regular combat regiments which wore the dark blue. Later the name of Invalid Corps was changed to the Veterans Reserve Corps.

2) Some veteran soldiers of regular volunteer regiments (like the 14th Iowa Infantry) re-enlisted and were placed with newer recruits into "Residuary Battalions" serving until 1865 (and longer) when their regiments mustered out at the end of a three year term of service in 1864.

Now my question is: are these two paths related?

Does anyone know if the uniform of these residuary battalions was the same dark blue as their regular volunteer infantry regiments, or was the uniform of the residuary battalions sky blue like that of the Veterans Reserve Corps?

Is there any connection between the Residuary Battalions and the VRC, or were these organizations for veteran soldiers still serving until 1865 two completely different and independant operations?