homepod minis

hpod mini

What I'm trying to do is play itunes music from my computer speakers in one room and from my minis in another room. When I check the mini icon in AirPlay the minis play, but the computer speakers don't, and vice versa. I can't check 'computer' in Airplay and the mini icon at the same time--one cancels out the other. I mean, the whole purpose of the minis is to fill both rooms with music. If I can only play them separately, what's the point ? Thanks for your attention.