RPI4 with LE 10.0 dual audio mode

Hello

I have Raspberry Pi 4 with LibreElec 10.0 connected to my TV by HDMI cable.

I would like to use Kodi in dual audio mode, because I would like to watch movies with my wife when children sleep;) so I need connect two Bluetooth headphones to RPI4

I activated dtparam=audio=on in config.txt. so I can use analog

Next i tried:

PulseAudio - Official Kodi Wiki

Step 1: Edit /etc/pulse/default.pa

load-module module-combine-sink sink_name=combined

Unfortunately I can't edit this file because of problem with permission. (warning no write permission)

I can't find any way to edit this file.

Can you help?

I tried:

mount -o remount,rw /

don't help

Maybe you have any other idea how to connect two Bluetooth headphones to raspberry pi 4 with LE?

I will be grateful for any help

Thank you so much Da Flex for your help.

I create new file "custom.conf" in folder /storage/.config/pulse-daemon.conf.d.

This file contain:

"load-module module-combine-sink sink_name=combined"

Unfortunately this is not change anything.

There is no any new option in settings-audio.

Should I do something more in this file to have option to connect 2 devices?