It is possible to create new service :

/etc/systemd/system/multi-user.target.wants

[Unit]
Description=qml-launcher Service
After=

[Service]
ExecStart=/home/bin/QmlBoot.sh
ExecReload=/bin/kill -HUP $MAINPID

[Install]
WantedBy=multi-user.target

As there is an overlay created by inmusic, the original script is in

/media/az01-internal/system/etc/overlay/systemd/system/multi-user.target.wants