The home button for the iPhone 6 is a physical button, and software does not control it. I guess I misunderstood your post, I was thinking two home buttons, you meant the button and the assistive touch, but you meant both daughters, with each of them having an iPhone 6. As far as the actual problem, is it just that Touch ID will not work, or is it that the Home Button does not work at all? There is a difference. If it is just Touch ID, then follow the troubleshooting steps I provided earlier, including contacting Apple Support if those steps do not work. If the Home button does not work at all, then you are going to have to see Apple, that is hardware. If you believe it to be a software issue, then create a current backup of the phone and restore it to that backup. If you still experience the problem, restore the phone to factory, and set it up as a new device, not using the backup and test. But Touch ID can be hardware or software.