QMK Userspace: How to use a community/userspace layout but have my own rules.mk or header files?

Hello,

On my keyboard's keymap folder, I want to utilize a generic layout which I defined on my userspace, but I want to have my my own rules.mk file and custom headers.

Let's say in my userspace I have /keyboards/preonic/keymaps/arda/ folder (the name arda may be different), where rules.mk and some custom headers and maybe some encoder, oled, whatever custom codes are stored. However, for this configuration, I want to utilize /layouts/ortho_5x12/arda/keymap.c file.

Theoretically, I could make a keymap.c file and inside it I could simply #include "../../../../layouts/ortho_5x12/arda/keymap.c" but I'm not sure it'll be correct, and I want to make this somehow portable, independent of the folder name, something like #include QMK_KEYBOARD_H.

How do I do this? What's the correct way? I simply want to use a layout but include my own custom configuration. I checked the docs but this was not clear for me.

Thanks in advance!