I have a family plan with 3 iPhone's. On launch day I will be upgrading two of these lines to iPhone 4. I will also be adding a new line to my family plan, and getting an iPhone 4 for that line. Will this be a problem, or over the limit? I understand that iPhone is limited to one per new customer, and one per line for existing family plan customers, but I haven't seen any answer for this specific situation. Thanks for any advice.