The old story can stay in the family without remaining the only explanation.

Families keep explanations the way they keep furniture. A story about why someone left, why two people stopped speaking, or where the money went gets settled early and repeated until it feels like a fact, usually because it was the version that let everybody carry on. Adding a second explanation does not require calling the first one a lie. Most family stories are true and partial at once.

If an old account has never quite fitted, ask a different relative what they remember. Hold the new version beside the old one rather than replacing it.