Axis:
XYZ = linear
ABC = rotational
UVW = linear
Not a rule, they can be changed to whatever is needed, but makes it easier to keep track
Simplest way i can think of is to do a config for 4 axis and 4 tandem axis, then edit the ini file to to rename the tandem axis, those will be named X2,Y2,Z2,A2 by PncConf.
Be aware that if using limit switches, the HOME_SEQUECE will be negative for all joints and that will prevent homing, so make the positive and number them as they should be homed.
The hal file has to be edited also as this will result in two joints for each axis, so 4 of them have to be added their own axis "tittle".
Or give the new tool by BigJT a try, see if it does what you need and report back as he is actively developing it:
forum.linuxcnc.org/27-driver-boards/4599...ration-tool-features