Explanation
To add custom icons to the Life Events and Business Milestones, you need to upload them as static resources in Setup > Custom Code > Static Resources. You also need to update the Icon Name field on the Life Event and Business Milestone objects to match the name of the static resource. Verified References: : Salesforce Financial Services Cloud Implementation Guide, page 58.

To model a requirement where more than one person can be joint owners on a Financial Account, the Admin can map additional owners using the Financial Account Role. The Financial Account Role is a junction object that links a contact or an individual to a financial account and defines their role or relationship with that account. By using Financial Account Role, the Admin can add multiple owners to a Financial Account and specify their ownership percentage, primary status, and other details.

Explanation
If a client is associated with more than one Household or Group, their records will get rolled up to the household selected by the advisor for record rollups. A Household or Group is a construct in Financial Services Cloud that allows you to group related accounts together and view their aggregated financial data and activities. A client can belong to multiple Households or Groups, but only one of them can be selected as their primary Group for record rollups. The primary Group determines which Household or Group will display the client's records in its summary components or related lists. The advisor can select or change the primary Group for a client using the Primary Group field on the client's record page. Verified References: : Salesforce Help Article 6