Dear Rachel,
I read your post on the internet forum Q&A the day before yesterday and I would like to share my opinion with you.
I think it is a very important topic and more people should deal with it. You see bank loans can solve some very urgent problems and in those cases they can be useful. But in other cases they are so dangerous. Most students are not careful enough to decide well. People who spend a lot of money just because their friends do so are not responsible. I think your sister, Becky is not old enough to move away from your parents. She should wait until she finishes university and finds a good job. Renting an flat costs a lot of money and she will have to buy food for herself, too. In my opinion she should stay at home, study hard and look for a good student job. This way she would be able to save some money for the future and she would have the opportunity to find a well-paid job after university.
I hope I could help you with my answer and everything will be OK with your sister.
Best regards,
Kate