Cell phone plan sharing is the subject of this question. I'm thinking of putting my 17 year old brother on my cell phone plan. I am 18 and a U.S. Marine and my cell phone plan is my only credit program I've ever had and I don't want to screw it up. He has a job but what if he loses it and can't pay his share. My mom says she will take the phone from him and use the phone and pay for it. But she is often out of work because she is ill and her income is not always steady. I think I've already answered the question, but needed some feedback from others.