i have iPhone 6 128, so has iPhone 6 64. I'm upgrading to ip7 and want to give her my iPhone so she gets more storage. Then I'll sell hers. We're both on att but not on the same account. Is it as simple as back up both. Restore both from others backup and swap SIM cards? Or is there something I'm missing? I'd be doing it now. A few days before my ip7 arrives since she's got storage issues.