Since the mother stayed and the cygnet found its way back to her, we would suggest that you not try to get them back to the pond. Mother knows best and she may know that the cygnet may go back down and she might not be able to get back down again. Also, the mother is the main caregiver so dad is not going to really worry about the cygnet as long as it is with the mother and he feels that they are safe in the new area. If the mother should get back into the pond, then you need to get the cygnet back up with her and the dad. If the dad wants to join the two, it sounds like this is a possibility. Good luck. The Regal Swan