Do you want to share a system with someone else? That is possible. Create a user to share a system with this person. The user can view the system in his own account.
Note: You only create a user, not a driver. A user could only enter the online account, a driver is listed within the ride registration, but can also view his or her own private tunes in their own account. If you want to invite someone as a driver, do this with drivers in your online account.