Recommendations for idiot-proof software to backup data to multiple external HDDs? (Windows)

Idiot is a strong word. However, I'm currently working a job with a group of people who are certainly capable of ruining their summer by losing all their data. They run their daily data collection (mineral exploration, core logging, etc.) off an external WD Passport from lord knows when (USB 2.0). This hard-drive travels with the work laptop, and any files they're using, manipulating, etc. are being run directly off this drive. There is obviously a potential for general HDD failure, but also for some clown to drop the hard-drive or otherwise damage it, thus killing the data. They have no backups.

So I've purchased a couple of 2TB external 3.0 hard drives to make redundancies of their data. I'd like to use one of the drives for weekly backups and one for backups every day or every other day. Is there an easy and recommended piece of software that will make this easy so I don't have to manually copy over their 250GB database every day? Something that will always correctly recognize one drive as the source and one as the recipient and only move what's new/changed? And also something that I can set-up and leave in a manner that they won't ruin everything when I leave this job in September? Everything here is on Windows 8, 8.1, or 10.

Your advice and recommendations are appreciated.

tl;dr - Need software to make periodically backing up one external HDD to two others as easy and foolproof as possible. Windows only.

Built in Windows backup. Once you set it up, every time you attach the USB drive, it should ask you to perform a backup. It does differential backups, so you can go back to points in time.

If you want it to be more hands-off, those drives in a FreeNAS box would be able to do the same thing. You'd just have to do the initial config. It would be doing backups whenever the FreeNAS box was network accessible.