You can’t let anybody else drive with your account, not even your friends or your family.
The friends and the family are allowed to drive a Poppy themselves, but they first have to register via the app before driving with a Poppy vehicle.
If you have a Poppy account, other people are of course allowed to join you as a passenger during your trip in a car. On a Poppy scooter, you can take another passenger. This person must always wear a helmet for his own safety.