The instructions on how to add a family member to the scale/account is badly out of date - the software now does this in a different way. But aside from that, how can the 'guest(s)' review their weight over time via the app? They don't necessarily want to log in with my credentials. In fact, how does the scale even know who it's weighing? There's really little to no information about this basic issue on the Withings app and site.