A couple of points for incorporation into the knowledge-base at the head of the thread :

When there are multiple passengers travelling together on the same booking, who is entitled to the EC261 compensation ? Is it the lead passenger who actually paid for them all, or does each passenger get their own compensation ? Can the lead passenger make a single claim on behalf of everyone (which could include shared duty-of-care costs such as 1 hotel rom for 2 passengers), or does each passenger have to make their own claim ?