using airplay from 4 devices to one airport express

this is really about airplay, but when I want to post, the only community I find is Airport Express ???

I have 4 units: iPhone 7, iPad pro, Macbook Pro and iMac 27"-5K. I have started trial of Apple Music. Everything works fine.... BUT it is a nag that if I stream from one unit to the airport, which is connected to my digital amp via optical cable, I cannot use any of the other devices to stop or change or even see what is playing or from which device. Also it is a nag that if I for example use the MacBook Pro as source and happen to close the lid, the stream is stopped.

I have not found any settings that allows me to do this. I run Its 11.4.1 and macOS 10.13.5.

What I would really appreciate would be a "common" app, that will allow me to control the flow of the streaming, from any unit on the same wifi/ using same Apple ID !!!

I have this option when I stream from my network connected Node2 from Bluesound. There I have "the same" app on all 4 devices and and can control the music and source with ease. Mostly I stream from my NAS which have a copy of my iTunes library. They also offer online services like Spotify and Tidal, but no Apple Music, alas.

so... is it a feature from Apple which I have not discovered, or will it come "soon"???

:Airplay is very limited.. even airplay2 will not do what you want.

But there are third party apps like airfoil that are worth a look.