how to add new satellite to vu+ duo 4k receiver?

Create a custom satellites.xml with the satellites you need and send the file to /etc/tuxbox or /etc/enigma2

here is a guide to setup openvix

https://www.openvix.co.uk/openvix-builds/Guides%20and%20Tutorials/VIX%20Manual%20Vs%201.1.pdf

if the satellite you require is missing then you need an updated satellite xml file, like suggested above

you can download a sat xml from here

satellites.xml creator