I regularly pull photos off of my iPhone and store them in my Synology for safe keeping (I also protect against the nuclear option by backing up my Synology to AWS Glacier).
This has worked well for me (except I'm still looking for something to help with organization—drop me a line if you have recommendations) but tonight I came across a new problem.
I wanted to put a Live Photo back on my phone after having archived it. I found the original photo, but when you pull them off, Live Photos become two separate files.
Both files share the same name (e.g., IMG_9273) but have different file extensions: the .jpg stores the primary still image and the .mov file stores the motion and audio around the still.
I tried copying both files back onto the phone, hoping that iOS Photos would know what to do with the two files, but alas, no—it could not be that simple. After a little searching, I discovered that OS X knows a little better how to deal with these files.
The short of it is: copy both files into OS X Photos. OS X Photos will automatically merge the two into a single Live Photo, which you may now export or AirDrop onto your phone.