How to add HomePod mini to other apple id account?

I bought HomePod for my wife. at the setup process, I had to connect it to my account because I am the “owner” of the home.. (she is admin).

The problem is the she can’t stream airplay from her Apple Watch to the HomePod, only I can do it because it appears as one of my Apple devices..

I tried to set her as a primary user at the app but the login fails (I don’t know why)..

One last thing, I am using Apple Music family account (if it’s matters..)

The scenario that works for me is:

At my Apple Watch, open Apple Music -> press airplay icon -> select HomePod.

I want it to work the same at my wife’s Apple Watch.

anyone knows what am I doing wrong?