i have seen this question posted before and i figured out how it seems to be coded. poor programming but here goes. i have the siriusxm web player open on my computer. then go to discover all channels. here you can add remove favorites by clicking on the star. .https://player.siriusxm.com/all-channels
Now here is the dumb part. the siriusxm favorites in the sonos app (was using the sonos app on my computer to make it easier.) only allows 18 entries. so if have added more favorites it will only display the first 18 selected on the sirius player… i found this out when i was removing favorites on the sirius all channels site that i didnt use, but were on of the 18 sirius favorites in the sonos app i saw that when i removed one from the sirius site it would be removed from the sonos sirius favorite section and then I would get another favorite here in the order that i seemed to have added them in the web sirius all channel sections.
so i would conclude that if you wanted to have 18 of your most listened to stations here you could remove all your favorites on the sirius site. wait until they all went away then add the ones you want on the app, then add any others you might want on the sirius app. in the car it is a different set of favorites. again seems like poor planning for ease of access.
probably easier to just browse and add them to sonos favorites. :)