Family traditions are often a mix of fact and fiction–where the fiction has been slowly, and sometimes unintentionally, added to the facts over time. The teller of the story may believe it because they heard it many time or because a beloved family is the one who told it to them. Other times relatives intentionally embellish stories of their own life with details that are not true or complete events that did not happen. They may tell the story so many times over so many years that they begin to believe it is actually more true than it is.
Write the story down as the person told it, including their name, date, and (if applicable) details of how likely it was their memory was accurate or if the individual appeared to be having recall issues.
Then work on seeing what parts of the story can lead to actual records.