Trados Business Manager supports the selection of assignees in a Language Cloud project after project creation, in the planning phase. Generally the workflow looks as following:

1. Open Reference data > Services and link necessary services (like Translation or Proofreading) with Language Cloud task types. To do that, select single service and click RWS > Link with existing task type.
2. Open Reference data > Vendors and link your vendors with Language Cloud users. You can do this individually for each vendor, or click RWS > Import missing users to download all Language Cloud users and create vendors in TBM.
3. Create a project in TBM, and link it with any Language Cloud project. You can do this by creating a project from TBM in Language Cloud or just by linking projects, if it already exists in Language Cloud.
4. In TBM project, create jobs and assignments, and select vendors in created assignments.
5. Save a project.
6. Click RWS > Trados Live > Plan project. The following dialog opens:
   
   In this dialog, you will find general information about a project (project name, deadline and location), as well as list of tasks from a selected Language Cloud project. Take a note that list of tasks will include only those tasks which have mapping established (between TBM services and Language Cloud task types).
   Current assignees column displays names of Language Cloud users which are currently planned for a task.
7. If TBM may find translation assignments in a current project which contains corresponding tasks (for example, translation) and have non-empty Vendor field, then vendors from those assignments will be pre-selected in the New assignees column. You're free to change this selection, by selecting any vendors you like. Take a note that vendor combo box contains only vendors linked with Language Cloud users.
8. You can also switch a toggle in the New assignee type column and then select user group in the New assignee column, if that is needed.
9. When you're ready, optionally check Complete project planning task and switch to translation when possible checkbox. If this box is checked, then after successful changing project plan (only after successful) TBM will send additional request to Language Cloud to complete the ongoing Planning task and move on over workflow (this usually means switching to Translation).
10. Click Apply to start operation. You will see 1 or 2 confirmations with information about results of the operation (first about setting a new plan, and second about completing planning phase, if needed). Both messages may inform about successful completion of the operation or contain information about errors occurred.