The following FSC features should be part of the solution design for managing confidential deal information and notes sharing among deal teammembers:

Financial Deal Management: Financial Deal Management is a feature in Financial Services Cloud that allows you to track and manage complex deals that involve multiple parties, products, and stages. You can use Financial Deal Management to store confidential deal information such as deal name, amount, status, or participants. You can also use Financial Deal Management to associate opportunities, products, or tasks with a deal.