When a project manager identifies stakeholders who will be impacted by the delivery of a new product, it is important to update the communication plan to reflect these findings. This ensures that all stakeholders are informed about the project's progress and how it may affect them, fostering transparency and managing expectations.
References = The answer is based on standard project management practices and the typical use of communication plans in stakeholder management. For detailed information, please refer to the CompTIA Project+ Study Guide and other official CompTIA resources.

Explanation
The project manager should have a meeting with the project sponsor and main stakeholders first after discovering that some of the legal requirements have not been addressed during the project concept preparation. The project sponsor and main stakeholders are the key decision-makers and influencers of the project. They have the authority and responsibility to approve or reject any changes to the project scope, budget, or schedule. Having a meeting with them can help to communicate the issue, assess the impact, explore alternatives, and seek guidance on how to proceed with the project34

Obtaining approval for changes to software is crucial to ensure that the changes do not negatively impact other functionalities of the software. Approval processes typically involve a review that assesses the potential impacts of the change, which helps in mitigating risks associated with the change.
References = The answer is based on standard project management practices and the typical use of change control processes in software development. For detailed information, please refer to the CompTIA Project+ Study Guide and other official CompTIA resources.

The project manager should distribute an agenda before a call to ensure all meeting items are addressed and the correct participants attend. An agenda is a document that outlines the purpose, topics, and objectives of a meeting. It also includes information such as date, time, duration, location, attendees, and roles. Distributing an agenda can help to prepare the participants for the meeting, set clear expectations, and facilitate a productive and focused discussion12

During the project closure phase in the waterfall methodology, it is crucial to validate the deliverables to ensure that all project requirements have been met and the project outputs are complete and satisfactory.
Additionally, reconciling the project budget is performed to ensure all financial records are accurate and reflect the actual project costs, which is essential for the formal closing of the project.
References = CompTIA Project+ Certification Study Guide (PK0-005)