Make room for the other version
Ask what the other person understood before assuming that you are arguing about the same facts. For a message about how to ask a parent about end of life wishes, use this factual base: record the care task, health instruction, schedule, cost, decision authority, and current risk.
Correct the record precisely
Correct only what you can support, acknowledge any real impact, and propose a practical way to prevent repetition. Assign one decision or task at a time and confirm who will do it, by when, and with what information. Make the immediate next step clear enough that the recipient can answer without reconstructing the entire history.
Agree on a testable next step
Do not remove the cared-for person's voice, shame a relative, or promise care you cannot sustain. Use clinicians, safeguarding, emergency services, or legal advice for neglect, abuse, incapacity, or immediate danger. Do not recruit an audience, publish private evidence, or turn a misunderstanding into a campaign about character.