I have so been there and done that! This past October, my husband was offered a promotion at work that required us to move. We only moved 2 hours away, but still, it's a lot to consider. We also have 2 small children (kindergartner and 2 1/2). I am a teacher so of course this couldn't have happened at the end of the school year when lots of schools are hiring for the next year. That would have been too easy!
With his company, if you don't take a promotion when it's offered, you can pretty much kiss any chance of a promotion goodbye for a long time. But we still had to considered the pros and cons.
He got a raise, but we also now have to pay childcare (my mom kept the kids before). Had to sell our house, find a new one, etc. In the long run, there was no easy answer, but we did decide for him to take it because looking down the road, it will help him in the future.
I teach high school and was VERY fortunate that a teacher was retiring mid-year, and I got her job. We lived seperately for a little while so he could start his new job and I could finish my semester at my old high school.
As a high school teacher, I have seen several times where a senior would stay behind with friends to finish the year. I can completely understand your teen not wanting to move. I don't know if that would be an option for you. We moved from a military town so a lot of them had already moved numerous times, etc.
Hope this helps.