You can think of your wallet configuration file like a “treasure map” back to your bitcoin. It includes the directions that an open-source multisignature tool needs in order to reconstruct your vault, which means that it reveals the balance of your vault but does not give the person holding the file the ability to spend from the vault unless they have 2 keys. Unchained keeps a copy of this file at all times. Your inheritors would not necessarily need a copy of this since Unchained can assist them with the transfer when the time comes.
That said, some clients may feel more secure sharing the wallet file with their executor. This divulges the current balance of your vault but ensures that the executor has the ability to reconstruct the vault if something happens to Unchained and you simultaneously before the executor can legally recover the bitcoin.
Note: Digitally backing up your multisig config file in a secure location such as a password manager is critical for your vault security. Read our blog post about what they are and our Knowledge Base article on how to download yours.