KLM and legal and financial matters related to claim

pysifr

KLM cancelled our flight and rebooked us on a later flight. We arrived at our destination 12 hours late. KLM have stated we are entitled to compensation, according to the EC Regulation 261/2004. But they have asked for a handwritten and signed letter of authority and the letter should confirm that I have no objections to handling all legal or financial matters related to this claim. I don't trust them at all - what is the intention behind this confirmation that I will handle the legal and financial matters? 

eskbanker

I presume they're just trying to ensure that there aren't multiple parties making this claim, e.g. other passengers on the same booking or legal firms?