While it is probably theoretically a good idea to ensure that you vital documents are physically apart from your house (I was once told even a bank safe deposit location within driving range of your house is 'too close' in case a natural disaster hit, which is of course what Susie is referring to), the idea of both *MAILING* copies of my 'vital records' (social security numbers, account statements and the like!!!???) to *FRIENDS or RELATIVES* is somewhat frightening to me. I don't think I'd like to know that all this 'stuff' is somewhere that is not really under my control.
How about renting a safe box near your relatives and loading it up yourself every once in a while when you visit?