Legally Bitcoin is not the same as Banks in general which must have a special record of deposits for accountability, but you can still record bitcoins in a place that we know is a storage wallet, that's the working law of Bitcoin.

However, if you want to inherit and give to another party, you can still do that, even though legally you don't have a special note/letter, but you still have an asset record in your wallet according to regulations that you record yourself set for the assets you want to inherit, however you also have to be careful about using wallet records, keys and so on.