There are plenty chances to take photos without disturbing the young families.
This summer I ran into a number of House Martins running a food transport service towards an old stone bridge over a river that was crowded with kids and adults finding relief from the heat in the cool stream. I took off my shoes, wrapped the camera in plastic and joined them.
From below I could easily spot the receiving end of that food line without getting too close and took the following shots. Cropped down a fair bit however.