~ I think we should at least make backup file and should transfer in Bank Safe so that when they receive than they know how to retrieve it.
Seems you already have the answer to your question. But don't put the key or backup file in the bank. You can use a metal plate to save your private key or sheed phrase, then keep in your safe-deposit box or another secure place. And don't forget to use hardware wallet like
Trezor or
Ledger as the most secure wallet, use it and teach your wife or kids how to use.
You should really make yourself that responsible on teaching up things on your loved ones because its better that they do have knowledge on how to access things in case you passed away.
Some do really have trust on their family members where they could expose their PK even if they are still alive but there are who doesnt really like on doing so due to some trust issues.
This actually boils down on how a certain crypto earner or holder on how he would be securing out their assets.You wont really be that dumb on not to consider
on putting these things on safe and could be recovered by your loved ones.