the lighting and the background you may have to move your group to a better location in the room. the first photo below is of my sister and her family. although the tree is in the background, i zoomed in on the people. i see too many photos where someone has tried to get the whole tree in with the people. that is usually not a good combination so my motto is decide what your focus is (the people or the tree) and set up your shot accordingly.
the second shot below is a group of high school friends of my husbands (he is in red sweater). these guys have known 