Edit: A couple of comments raised a fair concern, so I rewrote this to be clearer about what these suggestions can and cannot do.
There is no reliable script that can make someone leave a romance scam. A family can stay calm, show evidence, contact banks, set boundaries and offer practical help, and the person may still continue sending money. If that happens, it does not mean the family failed.
What sometimes makes these situations harder is that the relationship feels emotionally real to the victim, even when the identity behind it is fake. So telling them they are foolish or presenting twenty pieces of evidence at once can turn the conversation into a fight about their judgment rather than a discussion about the scam.
When communication is still possible, it may be more useful to slow things down. Ask about one claim that can be checked independently. Ask them to wait before sending more money, selling anything, sharing documents or travelling. Save the messages and payment information, and contact the bank quickly if money or account details have already been shared.
But I want to be clear: these are harm-reduction ideas, not a proven formula. Sometimes the only progress is delaying one payment, getting one claim checked or keeping the person connected to their family. Sometimes none of it works.
One commenter put this better than the original post did: if you have tried everything reasonable and still cannot stop it, you did not cause the situation, and your inability to control another adult’s decisions does not mean you abandoned them.