@droftarts Thank you for your reply!

I have tried your solution and while I could not get just the A and B axes mapped, I did manage to do:

M563 P1 X0:3 Y1:4

Which made them move in sync and worked as expected.

M563 P1 X3 Y4

This did not work however. The AB axes would not move at all. Using X4 and Y5 also did not have any effect. The axes XYZABC would be numbered 012345 right?

Anyway, thanks for the reply!

I have 6 axes in total: XYZ and ABC. I have it configured as follows:

; Drives
M569 P0.0 S1                   
M569 P0.1 S0                   
M569 P0.2 S0                    
M569 P0.3 S1
M569 P0.4 S1
M569 P0.5 S0

M584 X0.0 Y0.1 Z0.2      ; set drive mapping XYZ
M584 A0.3 B0.4 C0.5	 ; set drive mapping ABC

When I try to do this gcode it works:

G0 X32.5 Y17.5
G3 X32.5 Y17.5 I0 J20

But when I try the exact same for ABC it doesn't move and instead the XYZ axes move.

G0 A32.5 B17.5
G3 A32.5 B17.5 I0 J20

I presume this is because I and J parameters are meant for XY, but as far as I am aware there are no parameters for added axes like mine.

Is it possible to change the configuration somehow or is it simply undoable?

Thanks!