Despite the fact that there is no provision for third party in the blockchain wallet process there are still known ways in which you can pass on your founds and grant access to your personal wallet and one of those popular way is to reveal your wallet key of back up phrase to your love ones in that way if any thing happens to you they have access to your wallet.
That's true, it is better if there is someone you love who knows about your seed so if ever something bad happens to you, they can still access to your funds. Imagine if you die and you have a huge amount of money on your wallet, if ever no one knows how to access your wallet then all this money will just be wasted, it will stay on your wallet forever and no one knows how to access it, even your love ones and family. You should always think about any possible things and secure the future of your family.