Explanation:

When a client requests a scope change, such as extending the project radius by 1 km, the project manager should first obtain formal acceptance for the work that has been completed within the original scope.
Following this, the project manager should submit a change request to address the new requirement. This process is in line with the PMBOK Guide's Change Management Process, which includes identifying the change, analyzing its impact, documenting it, and presenting it to the Change Control Board (CCB) for approval1.
References:
PMBOK Guide's Change Management Process For PMP Certification1.
Project Management Institute's official references for the PMP certification2.
Professional in Business Analysis Reference Materials provided by PMI2.

The Project Management Professional (PMP) emphasizes the importance of direct communication with project stakeholders to ensure clear and effective information exchange. When a stakeholder is not attending meetings and is seeking information through a family member on the team, it is essential for the project manager to engage directly with the stakeholder to establish proper communication channels. This aligns with the principles of stakeholder engagement and communication management, which are critical for project success. The project manager should request a meeting with the stakeholder to discuss project updates and expectations, and to integrate the stakeholder into the communication management plan.
(Project Management Institute. (n.d.). A Guide to the Project Management Body of Knowledge (PMBOK Guide) - Sixth Edition and other PMI published standards; Project Management Institute. (n.d.). PMI's Professional in Business Analysis (PMI-PBA).)

When faced with conflicts arising from cultural differences within a project that involves multiple organizations, the project manager should first seek guidance from the project sponsor. This is because the project sponsor has the authority and perspective to understand the broader organizational strategies and can provide direction on how to best address the cultural issues. Additionally, the sponsor can facilitate the development of a strategy that aligns with the project's goals and the organizations' cultures123. References:
* Managing Cross Cultural Differences in Projects1.
* Cultural Diversity in Project Management: How Project Success is Perceived in Different Cultures2.
* Cultural Differences: Knowing the Nine Dimensions of Culture to Succeed in Project Management3.

To avoid the risk of a project schedule delay due to the project and operation teams' inability to operate the Building Management System (BMS), the project manager should have allocated proper resources for training on BMS within the project plan. This proactive approach would ensure that both teams are adequately prepared to operate the system effectively upon handover. Training is a critical component of project management, especially when new systems or technologies are implemented. It ensures that all stakeholders are competent in their roles and responsibilities related to the system, thereby minimizing the risk of operational disruptions and schedule delays.
: (Professional in Business Analysis Reference Materials1, PMI2)