If your phone messed up her phone, I would check into fixing that issue before getting another card and potentially ruining it as well. I would look over your apps and start removing ones you really don't need and see if that fixes the problem, or even trying a different rom as something there could be an issue as well.
One thing that is usually listed as a cause of sdcard corruption, in any device, is just unplugging it without unmounting from a PC/device. It is recommended, if you mount on Windows, to use the Safely remove device icon that pops up in your taskbar when a usb device is plugged in. This will prevent writes/reads from happeneing and ensures nothing gets written to the card when you unplug, thus corrupting data. While it generally isn't an issue, it can happen.
If the phone continues to corrupt cards though, I would take it in to Verizon, inform them of the issue and ask for a replacement under the manufacturer warranty as it is a defect. You might have to push it though as they'll probably try saying it's normal wear and tear.
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