Best option For Syncing Documents Directory Between Devices

I want to keep an apps documents directory that contains sqlite using core data files in sync across users devices. The sqlite files are the only files in the apps documents directory and simply need to be common to all users devices

Ive tried various methods from:

zipping up the sqlite files to send by email, which works with iTunes file sharing but not suitable for my needs as it can expose the files to other users devices and a bit "last year".

Ive tried using app groups to keep the directory common across devices http://ift.tt/1HXxfIk,

and

Accessing Core Data SQL Database in iOS 8 Extension (Sharing Data Between App and Widget Extension) but that simply did not share the directory across devices for me.

Ive sent the file to parse but pulling them down and re configuring the data was the problem there.

Tried using iCloud and even the Apple engineer gave up on that one

What i'm after is the simplicity of file sharing through itunes (being able to replace the sqlite files) with a bit more finesse and without the need to plug in the device.

Who would have thought keeping two devices in sync with info would be so problematic

Some considerations 1. The whole model can be synced in one go 2. Data does not need constant syncing facilities, a manual sync option would suffice