Sometimes customers write to us and want to know whether it is okay to have multiple family members log in to one of our Lines apps at the same time.
If you are part of the same family group on the same trip, we do not have technology- or policy-based restrictions that prevent actively using the same account simultaneously on a few different devices. In summary, you are free to share an account within your family while on a trip together.
However, the fact that we allow this does not mean that it is a good idea. If you share an account among family members on the same trip, you do so at your own risk, and you should consider whether the benefits are worth it.
The Lines apps and other TouringPlans.com tools are designed for use by a single person at a time, so there are not provisions that prevent actions on one device from stepping on actions initiated on a different device. For example, if two people tap "Optimize" on the same plan within seconds of each other from different devices, what happens? We don't know because this is not a use case we support or test.
In addition, each TouringPlans.com account has total control of all configurable options in that account. That means that if you share your username and password with a family member, that person can change your password, modify or delete your touring plans, post messages on Lines Chat under your username, change your username, delete a trip from your dashboard, and more.