What a great moment. However what could have made this composition even more stronger in my opinion if you had created more depth, captured the subjects flat on (not slightly angled as with the present composition), and created a tighter crop vertically.
I love the fact that you included the parents behind, which gives the viewer more insight to the composition, but having them more OOF would have been much better, as i find them a little too distracting in the background.
A tighter crop vertically would help to composition out abit as the dead space is kinda distracting, esepcially with the highlights on the window panes on the background.
I would have loved this even more if it were b/w, but the colours from the velvia are still great, the colours on the girl's dress give it almost a surreal, painting like look.
overall, great shot, captured a nice moment in time...