Hi John. No, most swans, regardless of species will kill a cygnet if it is not their own which is part of their territorialistic nature. This acceptance by non family members would be extremely rare.

Cygnets taken from their parents before significant bonding occurs is the reason for abandonment and even infanticide. If the parents have an inkling that something is wrong or different about the cygnet, this will also result in abandonment or death by parents. The Regal Swan
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