I guess this is a feature request unless I have something simple.
I would like different family accounts to be able to see all the devices available to the family without having to sign in under a different account.
For example, we use a computer with decent speakers in one room running the Spotify app. My wife and my self would like to cast from our phones to that computer. Only the one who is signed on at computer can even see that device in the mobile Spotify app.