Complex iP5S Trade-in Scenario

Besides being in China when we will likely be able to purchase an iP8 on September 16 - as they will be selling in an Apple store near my Shanghai hotel - my primary concern has to do with an accounting issue at my office.

My spouse's line is available for a trade-in, but her iP5S will fetch little money anywhere. The problem with using her line is that my office accounting will be confused with the idea that my office iPhone 8 is showing up on spouse's phone number which means I may have to personally pay for my office iP. There is also the problem is having to switch SIMs once the iP 8 is received.

I could outright purchase my current iP 7 then get an iP 8 on my own number which then means going to the open market to sell the iP 5S.

Of course this assumes that my order for an iP 8 will actually go through and be shipped sooner than the first quarter of 2018 which seems a likely scenario.

Is there another way of getting at this that I have missed?