multiple apps mixing : mpd + squeezelite

Hello
I use hifiberry dac with great pleasure and a great sound.

I want to use simultaneously mpd (volumio) with squeezelite and shairport.

at the moment mpd acquires the device hifiberry and creates a lock for other apps : need to kill mpd to start SL and vice versa.

Since there is no hardware mixer (next hifiberry version ?) how can we configure alsa to allow software mixing with multiple apps ?

This may bring some audio loss (how and where ?) but it will make life much easier switching from an app to another ...

Thx for your help.