Or you could just give your loved ones the password for your computer. I know it's hard to trust anyone else with a computer's master password, but if you can't trust your loved ones not to use the password when you're alive, then maybe you should rethink giving them your entire fortune when you pass away.
I am more inclined with that solution. Give the files to then in a way that are encoded, like a 'personal code', a hint, a little distortion. The objective is counterfeint a possible leak in those documents that you are not promptly aware of.