Hi rleutwyler,
Thanks for coming to Apple Support Communities for help with your Apple Music radio. It sounds like you want to know how the personalized station was created and if you can make changes.
Have a look at this page: Listen to Radio in Apple Music and scroll to "Create a custom station with Apple Music". A station is created from a song or artist. You can also use Siri on an Apple device to create a station. While you can't add further songs to the station, you can create another station if you'd like.
Have a fantastic day!