The short answer is no. The long answer is it's up to you.
The short answer is no. Nobody has access to your Continuity Vault except you unless it needs to be unlocked in the case of an emergency. In that situation, any Emergency Contacts that have accepted your invitation to act as an Emergency Contact for you will be able to access the vault.
The longer answer is that you may invite your Broker Dealer to act as an Emergency Contact. If you do, they will be able to access your vault in the case of an 'unlocking' event as well. As a note, you do have the ability to further restrict access to each of the Agreements / Documents you upload into your vault, so if there are are certain documents you do not want your Broker Dealer (or any other Emergency Contact) to have access to, be sure to manage "Download Rights" effectively.