Hi Wes, you paint a really complicated verbal picture. Is there any chance of a sketch, drawing or picture?
If I understand the problem, and I am not sure I do, the five sideways moving shafts could be mounted to a frame so that all five stay in a firm and fixed relationship with each other. No belt racking. On one shaft, you could have a spline and on that sliding pulley for the incoming drive belt.
That pulley stays fixed with the incoming drive system and the "frame" (five shafts with their own belt) slides the spline back and forth in the drive pulley.
I think I just muddied the description even more.
Ooops, the red lines on the shaft indicate the splines. Forgot to Label. I'm old I forget stuff, you will too eventually.