Did you sacrifice your middle child ?. That's a requirement I think.

Seriously. You need to grab a bunch of cables, your computer and the 520 or 1030 and try the assorted cables to see which does data. THEN LABLE IT !!!. Then repeat for the 2nd device and LABEL IT !!!. Then do not use for anything but charging those devices (in other words, don't lose these cables) and when you want to do OS updates use the labeled cable appropriate to the device. I finally did this, but I also use BT and the Garmin Mobile app to get routes onto the device as well as completed rides off, so don't have to use the cables for other than charging.