Thanks for the reply. I forgot to add that a few days later we saw the family all together. I would be surprised if the two groups I was referring to were both strangers, because the father of the local family is usually quick to detect and shoo off outsiders.

Also, is it just a coincidence that a few outsider swans would fly so close to a family they don't belong to? At least once I've seen a few fly right over the heads of the family while being pursued. It's not like they didn't have any other choice...