your individual shots are much stronger than your group shots....
the first shot, i like the concept, however, it think you would have made use of the tracks by having them walking on them, holding hands, maybe dad holding the youngest...
the second shot, whether the girls are posiitioned more to one side or not, it still looks like their parents are standing on them and it just doesnt work for me.
for the shots of the girls on their own...very well done...nice comp and post processing. I like that you have brought it close to the edge, without blowing it out and your eyes are spot on.....nicely sharpened without going overboard and making them appear fake like too many child togs do.
good job overall....my suggestion would be to work on posing groups