You could also have everybody lie down in a line and have everybody bend their knees. Have everybody look backwards and then the picture should be taken. It will be quite a fun picture! You could also make formations or stand in angles. Standing in 'v' formations with the father at the tip of the 'v' and the others standing in the 'v' formation is also fun.
You could also stand behind a tree, shortest or smallest member first and the taller ones behind. Have each one pop their head from behind the bark, such that one can only see the heads popping out of the bark.