A girl of 17 years old wants to travel with her sisters this year. Her family disagrees with me. What should I say?

There's a reason why the family doesn't agree. First of all, it's for your safety. Second, it may be an economic problem; Safety is the most important thing. How did your sister meet? Is it reliable? Many of them are liars, and girls' travel is easy to be cheated and used by bad people. You have to convince your family what measures you have taken to take precautions in all aspects, whether your destination is safe and whether your journey is safe. You also have to make sure to report the travel situation in time every day. Talk to your family, find out what the root cause of their disagreement is, and then discuss it.