Change menu in xml.file of OSMC skin

From a json file I get m3u8 streams + info. This I would like to put in a xml file, so that you can search through them and open them with a link. This I would like to update every day through a python script. Which xml file is used for the main menu in the OSMC skin?
I tried to change a mainmenu.DATA.xml file. For a short time I saw my extra link and than it disappeared with an update. So I would like to know which xml file is used for the main menu and if this can be modified.

Thank you for any help or indications where to look.