iPhone SE on iOS 9 - Possible to restore messages from an iOS 10 backup? I have an iPhone SE that was recently updated to iOS 10 by mistake.  Since it can't be downgraded, I've acquired an identical iPhone SE running iOS 9.3.4.  I know I can't restore a full iOS 10 backup, but is there any way to restore just the Messages from the iOS 10 backup?  

I don't just mean to extract and save them as a text file or something, I mean actually restore them in Messages so they show up as they normally would, as the history of the people being messaged.
No, the database used has changed between iOS 9 and 10, and as such you can't copy the messages database over, since iOS 9 will detect an error with the database and start fresh.