So my sister just got the iPhone 5 but now she's saying she liked her iPhone 4 better. I offered my 4S if she gave me her 5 and she agreed. My question is, how do I go about switching over the SIM cards? She has her own plan and I'm on a family plan with my brother meaning I am not the main account holder. Do both my brother and sister have to be present when swapping SIM cards or can I just go do it myself? Or is there an easier way of going about this. Any help is appreciated.