You can already select desired competency clusters and individual competencies from an existing template when creating an assessment. To do this, store a competency model in your assessment and navigate to the "Customize" button on the right-hand side. Make your desired selection here.
Alternatively, you can also make this selection when editing your assessment. To do this, navigate to "Competency model" in the left menu. Here you can reassign a template to the assessment. The newly selected template is displayed and you can select and deselect clusters and specific competencies individually.

If you delete an already assigned competency model and add a new one, your assignments in the scheduler will be lost.