How to Stop AppleID Message from Displaying

Hello!

I manage a lab with 40 iMacs, each with multiple user accounts. Every time I setup a new machine or a user logs in a different account on an existing machine, "Your Apple ID is now being used for iMessage and faceTime on a new Mac" displays on every computer. I click OK to close the box, but the message always reappears at random intervals - sometimes from the same iMac.

Yes, I do have a generic AppleID which I entered for updates. Anyone know if there is a terminal command to prevent this message from displaying?

Thanks!