How to get your own fn key on the keyboard and remap key combinations without crutches?

Question

Keyboard

Hello.
I replaced the logitech k310 (which can be washed under the shower) with a lenovo sk-8825. The first one was okay for typing and with multimedia keys, but the second one is still more convenient to type on. But I'm used to turning on / off the sound, changing the volume, putting the computer into hibernation via fn + f1-12. The problem is that fn itself is not defined in any way, and it and combinations do not have scan codes, but only a virtual key code (mute. vol_up, etc.). I wanted to assign the role of fn to the right WIN or ALT (I would grab the MENU, but sometimes I need it), but something hung at this moment.
Mkeys won't start at all.
Key remapper, sharp keys, keytweak, keyboard layout manager cannot be assigned from combination to combination.
How to cut yourself combos in the end? Where to dig?