Correct me, Your first switch is receiving all uplinks and acting as VTP server? Now if you do the warm stacking from the back plain , it would provision as stack member and would share the same configuration. In this condition is that you need same kind of switch. Second option, it if you have a spare catalyst switch, then connect as it on etherchannel from the front and follow the design guide to configure GLBP on both.  https://www.cisco.com/c/en/us/td/docs/solutions/Enterprise/Campus/HA_campus_DG/hacampusdg.html ... View more

You can stack second switch and dual home access switches to it. Don't forget to order 2 extra SFP's for first switch if required. ... View more