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 Reference: : Salesforce Financial Services Cloud Implementation Guide, page 58.

In an existing Financial Services Cloud org using the individual account model, custom objects are used to represent other assets, liabilities, and goals. These objects are related to the Account object via lookup relationships. For example:
The Other Asset object is used to represent non-financial assets owned by an account holder, such as real estate properties, vehicles, or jewelry.
The Other Liability object is used to represent non-financial liabilities owed by an account holder, such as mortgages, loans, or taxes.
The Financial Goal object is used to represent financial objectives pursued by an account holder, such as retirement planning, education funding, or debt reduction. Verified Reference: : Salesforce Help Article [10] : Salesforce Help Article [11] : Salesforce Help Article [12]

Explanation
The recommended approach for implementing Financial Services Cloud at Lake Tahoe Bank is to implement Financial Service Cloud in a new org (Green Field) and redesign business capabilities in the new org. This approach allows Lake Tahoe Bank to leverage the best practices and features of Financial Services Cloud without being constrained by their existing customizations and data model. It also minimizes the impact on users during implementation, as they can continue to use their current system until the new org is ready to go live. A green field implementation requires careful planning, data migration, and change management, but it can result in a more efficient and customer-centric solution. Verified References: : Salesforce Financial Services Cloud Implementation Guide, page 8.

Explanation
Compliant Data Sharing (CDS) is a feature of Financial Services Cloud that lets administrators and compliance managers configure advanced data-sharing rules so that they can improve compliance with regulations and company policies. Some of the things to consider when implementing CDS in Financial Services Cloud (FSC) are:
CDS in FSC allows record owners to grant access to their records to other FSC users. Record owners can use the Manage Participants component on record pages to share their records with other users who have relevant roles or permissions6.
CDS can only be applied to FSC objects and Account and Opportunity objects. CDS supports sharing for Account, Opportunity, Financial Account, Financial Holding, Financial Goal, Referral, Relationship Group, Action Plan Template, Action Plan, Action Item Template, Action Item, Interaction Summary, Interaction Summary Participant Role Assignment, Interaction Summary Participant Role Definition7.
To get the benefits of CDS, administrators must set organization-wide sharing settings for supported objects to the Private access model. This ensures that only record owners and users above them in the role hierarchy have access to the records by default8.
References:
Compliant Data Sharing
Work with Compliant Data Sharing

A possible cause for why the portfolio manager cannot see ARC when trying to set up relationships between two accounts is that he has not been given the permissions that enable users to view and manage ARC. To access ARC, users need to have certain permissions and settings enabled in their user profile or permission set, such as:
View Setup and Configuration
Customize Application
Manage Custom Permissions
Financial Services Cloud Standard User
Financial Services Cloud Admin If any of these permissions or settings are missing, users may not be able to see or use ARC properly. Verified Reference: : Salesforce Help Article 5