For the past few years, I've created a photo book of the best family pictures from the past year. I store these photobooks in a fireproof safe. I think that's the easiest way to pass down pictures since it's paper doesn't require decryption or passwords.
This summer I forgot the PIN of my iPad, because I didn’t use it during all summer. And it’s only 6 digits. I had, however, made note of the PIN elsewhere so I was able to unlock it. I have similarly forgotten PINs and passwords in the past that I didn’t use for a while. I recommend unlocking your safe at a regular interval, so that you remember the combination, if it uses a code lock. And even if it’s a key lock it’s probably a good idea to do it too, so you know where the key is.