Are there any reeds or other grassy areas in or around the pond. Many times, if intruder swans appear and the parents cannot fend them off, they will take the cygnets through reeds and other wetland areas to hide. Additionally, the mother swan can carry the cygnets on her back for long travels. Are you absolutely sure that the parents have not hidden the cygnets in some area or are carrying them on mom's back and these are not the parents that you are seeing? There is also the possibility that these are the parents and that the cygnets were injured or got flushed into an area away from the parents and these are the parents.

If the swan family is okay, you might see them return to another side of the pond or wetland area in a few days. The Regal Swan