so we added the third switch to the stack.  it turns out that there was only one stacking cable installed on the original 2 switches in the stack so we technically did not have to "break" the stack to add the new switch.   we first plugged the new switch in on an access port and allowed it to connect to the portal and any firmware needed.  once it had been green in the portal for 15 or 30 min we powered the new switch down and connected the stacking cables to form a ring and powered the new switch on.  once it came up and showed on line in the portal we added it to the stack.  after that there was about 5 minutes where the switches in the portal went yellow, warning about stacking config being out of sync.  no traffic was dropped and all switches turned green in the portal.  Meraki has also automatically scheduled a switch upgrade in a few days coincidentally so we will get a reboot for that shortly.    otherwise it looks good. ... View more

so i called Meraki support and they told me to follow the procedure @PhilipDAth described and suggested that there should be no downtime.  i will report back once i have add the switch.   chris   ... View more

When you say short disruption what do you mean?  Will the two existing switches stop forwarding packets?   thanks   ... View more

I have the wiring part down, lots of experience with Cisco classic stacking.  I was hoping for a way to just add to the stack like you can with Cisco classic switches so i would not have to take the network down or risk it going down. ... View more