The groups that the business analyst should work with to gain full alignment on a common program vision and strategy are senior leadership, IT leadership, and middle management. Senior leadership are the executives who have the authority and vision for the Salesforce implementation. IT leadership are the managers or directors who oversee the technical aspects of the Salesforce implementation. Middle management are the supervisors or team leads who manage the sales and service teams. These groups can help the business analyst define the goals, scope, requirements, and success criteria of the Salesforce implementation, and resolve any disagreements or conflicts among them. Business leaders, end users, and executive sponsors are other groups that may be involved in the Salesforce implementation, but they may not have the same level of influence or responsibility as senior leadership, IT leadership, and middle management. References:
https://trailhead.salesforce.com/content/learn/modules/salesforce-business-analyst-certification-prep/collaboratio
https://trailhead.salesforce.com/content/learn/modules/salesforce-business-analyst-certification-prep/customer-di

Explanation
The best practice that the BA should follow is to schedule additional discovery sessions with the sales users to understand what will be impacted by the changes. Discovery sessions are meetings or workshops where the BA elicits, clarifies, and validates the needs, expectations, pain points, goals, and priorities of the stakeholders for a project. Discovery sessions help to gather more information and feedback from the stakeholders, understand their perspectives and preferences, identify the gaps and opportunities in their current process, and demonstrate the value and benefits of the proposed solution. By scheduling additional discovery sessions with the sales users, the BA can better understand their challenges and requirements, and document a comprehensive list of the components that will be affected by the updated flow. References:
https://trailhead.salesforce.com/en/content/learn/modules/business-analysis-discovery/plan-and-facilitate-discove

Explanation
The type of documentation that the business analyst should utilize to better understand business processes so they can accurately scope the project is current state analysis. Current state analysis is a technique that involves assessing and documenting how a business process or workflow is currently performed in an organization. Current state analysis helps to establish a baseline for measuring the current state of performance, identify pain points and opportunities for improvement, and align with the desired business outcomes. Current state analysis can be done using tools such as interviews, observations, surveys, or process maps. References:
https://trailhead.salesforce.com/content/learn/modules/salesforce-business-analyst-certification-prep/business-pro

The level of detail that the business analyst should use for the process map and why is somewhat detailed.
This is because the process map should provide enough information to guide new users through the onboarding process, but not overwhelm them with too much detail that may be irrelevant or unnecessary.
Since the process will be repetitive, new users will learn and remember the details over time, and they can always refer back to the process map if needed. The process map should include the main steps, decisions, inputs, outputs, and roles involved in the onboarding process, as well as any exceptions or variations. The process map should also use clear and consistent terminology, symbols, and notation to ensure readability and understanding. References:
https://trailhead.salesforce.com/content/learn/modules/salesforce-business-analyst-certification-prep/business-pro