The project manager should first establish a clear RACI matrix in the project governance structure. The RACI matrix defines the roles and responsibilities of each team member, outlining who is responsible for making decisions, who is accountable for the outcomes, who should be consulted, and who should be informed. This will help to ensure that there is a clear understanding of who is responsible for assigning tasks and managing work assignments. This will help to prevent confusion and conflicts among team members, and ensure that the team is able to work effectively.