I know you want to capture your sweet bundles of joy opening their sweet bundles of joy, so let me lend you a few tips.
2. If possible, bump up your ISO. This will allow your camera to be more sensitive in the low light of morning or if you open presents by the light of the Christmas tree. (Again, check your manual on how to do this.)
3. If possible, keep your shutter speed at 1/125th or higher. This will allow for light, but won't make your pictures blurry (unless your kid is the Tasmanian devil). Keep your aperture as open as possible (meaning, use the lowest number possible). Remember, the lower numbers keep everything behind your subject blurry so if you're trying to take pictures of multiple people you'll need to bump it up.
4. Enjoy the morning! This is time you won't get back so don't spend too much time behind the camera. Get enough pictures to tell the story then put the camera away! Christmas morning is not a spectator sport. Go play with your kids & watch them enjoy their new stuff!