The PMBOKGuide emphasizes the importance of stakeholder engagement and project communication management. When a functional manager expresses concerns about the project's quality management techniques, it is important for the project manager to address these concerns while also maintaining the integrity of the current project schedule. Negotiating a mutually agreeable time for the workshops respects the functional manager's concerns and the project team's current commitments. This approach is consistent with the principles of stakeholder engagement and effective communication, ensuring that all parties' needs are considered and addressed in a collaborative manner1.
: (PMBOKGuide - Sixth Edition, Section 10.1 - Project Communications Management)