If you want to use the ZUS of others, you would probably receive a message saying "This ZUS is currently used by someone else. " and then you would click send. By doing this, a notification would be sent to Owner and he needs to share his ZUS to you so both of you can use the ZUS.
If you have more than 1 phone, you may just log in the same account and that would enable you to access same setting or ZUS in both phones.
* UI may be different in latest app version