We have a Next plan, two phones. I have an S6 Galaxy Edge+ with a cracked screen, husband has an iPhone 6. He is/was eligible for an upgrade and preordered the iPhone 7. I am not yet eligible but am willing to pay the upgrade with trade in fee. Can I somehow use his iPhone 6 as the trade in phone and continue to make payments on my Galaxy as well as a new iPhone 7? My phone still works I just don't want to swallow the $500+ payoff yet. Thoughts?