Compare what would change the trip
If one notice says “West entrance” and another says “South entrance,” mark the entrance as unresolved. Ask the organizer and keep their answer with the event. Update the shared plan once rather than distributing both documents as current instructions. Keep one line per disagreement. For example, “Entrance: original notice West, second notice South. Confirm with event desk.” Unchanged details can stay on the plan while that question is open.
Identify the version, not just the email date
A relative can forward last month's PDF today. Check the document's own issue date, event name, organizer and any revision note. Also check whether both notices concern the same session. An entrance change for the morning group may leave the afternoon group's plan untouched.
Update the people already acting
When the organizer confirms the correct entrance, update the shared event and send the correction to anyone already travelling. Label the earlier notice as replaced so a later search does not resurrect it. If you cannot get confirmation, keep a contact route and tell the group precisely which detail is uncertain.