Here are two quick tips for photographing families or groups of people.
1. Make sure you take depth of field into consideration. Download a free depth of field app to your phone and take it with you. Then, try to keep your subjects as close to the same focal plan as possible, and make sure you set your aperture deep enough to keep everyone in focus. Also, leave yourself a little extra wiggle room, because in a group of people it is likely that someone will move slightly, and you don't want your depth of field so narrow that they fall out of focus if they do.
2. Use a tripod. The tripod will allow you to move about freely, keep your camera still and give you more options later on if you need to switch out a person or two to make the final image beautiful.