Proper drive assignment when adding DC1 for rotary axis

[CRM]

I am trying to add a DC1 to an ALLIN1DC system that was previously configured and working as a 3 axis mill.

I am following the directions provided by TB245 (Rev3) "Adding a DC1 4th axis to an ALLIN1DC System.
Mounting and +Vm, -Vm & drive fault wiring has been completed per instructions.
Step #9 instructs me to go into the config screen and change parameter 300-303 to 2,3,4 & 1 respectively. I understand this is because the DC1 takes the "Axis 1" position and moves all the ALLIN1DC drives UP one number.

But here is where I get completely confused:
Do I have to change the encoder assignment parameters? For example, the X axis encoder was (and remains) connected to encoder input #1. Does that mean I now have to change parameters #308 from 1 to 2 so it associates with what is now drive #2 on the Allin1 board? (and so on for the other two axes)
Or should I move the encoders up one position on the inputs, and use Encoder input #1 for the rotary axis?

Throughout the manual, when talking about a rotary axis, they seem to refer to it as a "fourth axis"...but if I wire it to the DC1 (because why would I want to have to re-wire the other three axes) it is actually connected to "axis 1". So, what am I actually doing when I change the drive mapping parameters? Does that allow me to keep all the motor tuning parameters that are already set in the PID table the same?

I guess what I'm asking is when a table says "axis" does that refer to my axis labels X,Y,Z,A; or does it mean the axis physically connected to drive 1, 2, 3, 4?
That is what is confusing me when I'm looking at the PID table in the motor tuning tab, parameters to assign encoder inputs and the like.

[cncsnw]

No. The DC1 becomes drive #1. Typically you would use it to move a rotary table that is axis #4.

When you set P300 - P303 = 2, 3, 4, 1 then you are telling CNC12 that you want:
Axis #1 (X) to use drive #2 (the first drive output on the Allin1DC)
Axis #2 (Y) to use drive #3 (the second drive output on the Allin1DC)
Axis #3 (Z) to use drive #4 (the third drive output on the Allin1DC)
Axis #4 (A, or whatever) to use drive #1 (the DC1)

The encoder inputs on the Allin1DC remain encoders #1 - #6, regardless of whether you have connected any DriveBus devices such as a DC1. So you just plug the fourth axis encoder input encoder input #4; make sure P311 = 4; and leave P308 - P310 unchanged.

The fourth axis uses the fourth line of Jog Parameters, Motor Parameters, PID Parameters, etc., regardless of what drive number is happens to be using.