Hello In order to add multiple users to a chest you should manually write [Private] and the IGNs of the people who you want to have access to the chest on the next lines. Example: [Private] ItsGuih Alex_Markey Vislo
Along with that functionality that ItsGuih provided above you can use the /lockette command. How it works: Right-click the sign you want to modify Type /lockette (line number [which is 3 or 4 since line 2 is your name]) <IGN of the player/text you want to add to your sign> And you will be able to let other people access that chest. Have a great day/night.
