Encrypt the file with a secure password or key, maybe using AESCrypt. Email the encrypted file to the relevant parties. Put the password to the file in your will (keep it under appropriate trusted guard, to be released only on your death). As long as the will and the encrypted file are kept apart until after your death, the file will remain secure until then. You can also modify the encrypted file as things change, encrypt with the same password, and resend the file.
There's still the possibility that their computer is compromised after you die and they decrypt the file. They could reduce this risk by opening it only on a known-secure system (e.g. an Ubuntu LiveCD boot), if it really matters. In any case, this greatly reduces the security exposure by not have this file sitting around for years for anyone to read.
Maybe they were just trying to show how the CDs might might sound if you try to play them? play them?
Yo dawg, I heard you like comments, so I made a comment on your story about comments on comments, so you can comment while you comment.
There's a difference between something you have on you (e.g. a key to a lock, DNA, fingerprints), and something you know (e.g. combination to lock, password). It's easy for police to show whether you have something. It's not (currently) possible for police to determine whether you know something. I think that an encrypted drive should be treated like a locked safe. Given the proper warrant, AFAIK the police have the right to try to break into that on their own if you don't want to open it for them - but not to compel you to give them the combination to it. The same way, they should be able to try to break into encrypted files on their own, but not to compel you to give them the password. The only big difference between safes and encryption is that breaking encryption is far more difficult, so the courts will be more inclined to ask you for the password than just break in on their own.
This is the equivalent of a car with a steering wheel that has fingerprint sensors on it, at the 9 and 3 o'clock positions. If it is unable to read valid fingerprints, the engine stops and the steering wheel locks in place.
It's safer because it doesn't let someone steal your car (be it your child, or a thief), and it forces you to drive with both hands on the wheel at all times.