Relatives are predicting her whole future from one weak physics test

Daughter is 15, grade 10, IB. She did badly in one physics assessment. Not a fail, just well below her usual. Since then every call from the relatives comes with a prediction. She won't get engineering. She should start coaching now. Someone's son was also like this and look where he ended up. She hears all of it. I want it to stop, and I want to focus on what actually went wrong in that paper, which as far as I can tell is two topics she skipped. How do you shut this down with relatives without a fight?