on inventory click:
if inventory name of current inventory of player is "Inv 1":
close player's inventory
Open chest with 4 rows named "Inv 2" to player
if inventory name of current inventory of player is "Inv 2":
close player's inventory
Open chest with 3 rows named "Inv 1" to player
command /inv:
Trigger:
open chest with 3 rows named "Inv 1" to player