I am in the middle of a basement remodel at my parents house and I am trying to decide which switches I need to convert the current setup into a smart setup. Please see attached for reference. Currently I have a 3 gang box at the bottom of the stairway, one switch is in 3way with the switch at the top of the stairs (zone3), one is in 3 way with zone 2, and one is in 3 way with zone 1. I have a 2 gang box with the other ends of zone 1 and 2 by the couch, these are dimmer switches. 

I want all zones to be smart, but only need dimming capabilities for zones 1 and 2.

Thanks for any help.

Ryan