I have a Macbook Pro 2013 running Sierra and am having sudden, serious problems using FCP 7 Studio (all was fine until recently). I have been troubleshooting the issue but it's only brought more trouble so far. Because there's debate about the health of using FCP 7 with anything later than 10.6.8 (they say each subsequent update further destabilizes it), I want to downgrade my Macbook to at least what it originally shipped with - Mavericks. So I will reinstall the OS. However, my Time Machine backup that I'll need to feed back onto the Mac is...perhaps...from a time when I used a later OS than Mavericks. I am simply unsure, the chronology is muddled in my mind. My question is: If I go back to Mavericks, and then try to use a Time Machine backup from a time when I was using, say, Sierra, is that gonna mess things up a little or even a lot? Would TM and/or my MBP even allow me to do that? Is the operating system itself saved in TM?? Thanks for any help.