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 Reference: : Salesforce Help Article 6

To create a relationship between Rachel and her attorney before assigning the reciprocal role of "Attorney", the Wealth Advisor should create a Contact-Contact Relationship between the primary member of the Adams Household and the attorney. A Contact-Contact Relationship is a junction object that links two contacts or individuals and defines their relationship with each other2. By using Contact-Contact Relationship, the Wealth Advisor can capture Rachel's extended network of relationships with people outside of her household. Verified Reference: 2

Explanation
The following OmniStudio tools should be recommended to generate the prefilled PDF:
OmniStudio Action Document Generation, which is a tool that allows users to create documents from templates and data sources using OmniScripts and Integration Procedures. By using OmniStudio Action Document Generation, the consultant can create a document template with placeholders for the contact and address information and generate a PDF file from it using an OmniScript.
DataRaptor, which is a tool that allows users to extract and transform data from Salesforce or external systems using Integration Procedures. By using DataRaptor, the consultant can create a data source that retrieves the contact and address information from Salesforce and maps it to the document template placeholders.