Don't do this with her, she's not smart....I guarantee she just maxes them out and moves on to the next higher interest rate card. I have a card I never use and one that I use JUST to make credit purchases to raise my credit score.....Even if she was balling, having a bunch of cards is financial suicide. Unless you desire a higher credit limit when you can afford it, DON'T just start collecting credit cards. You'll wind up in a never ending circle of paying them off with other cards.