Path to source code LCNC

I am working on Pull Request for PncConf
forum.linuxcnc.org/gmoccapy/55011-lcnc-2...-g43?start=10#320344

My modification works, but they use absolute pah:
I need way to find "realtive" path in source code. It must work in RIP instalation and package instalation.

I would like ask you for help.

"Python can find the path to the running code with the __file__ system variable."

I know it now.
It's even used right here:
github.com/LinuxCNC/linuxcnc/blob/1c72d4...cconf/pncconf.py#L33

"In both cases you probably need to use the Python path manipulation functions to assemble the required path."

stackoverflow.com help me with it. It is not problem for me.

Now I have enough information to implement my original plan.
Create new files in the linuxcnc/src/emc/usr_intf/pncconf folder and then copy them to the new LCNC configuration using pncconf.

However, @Aciera came up with a better idea.
He doesn't want to create new files in the linuxcnc/src/emc/usr_intf/pncconf folder.
He wants to use the original data from the configs/sim/gmoccapy folder.
The advantage is that there will be no unnecessary duplicate data in the source files.

The problem is that I don't know how to define this path cleanly: configs/sim/gmoccapy
This path is different for RIP installation and different for package installation.
github.com/LinuxCNC/linuxcnc/blob/40fe3e...rc/configure.ac#L702
github.com/LinuxCNC/linuxcnc/blob/40fe3e...rc/configure.ac#L724
I think this might solve my problem, but I don't know how.