Default assignment fields based on custom job attributes

Summary:

Hi, we have an existing HCM Design Studio Field Modification Rule Type configured on the Worker Assignment business object that, any time the job code is changed for an employee, 2 custom assignment fields, a Bonus Plan and Bonus Rate field will be defaulted to the bonus plan and rate defined for the job (also 2 custom attributed defined for the job code). How do we accomplish this with VBS? It is possible? We would need to trigger this in any flow where job code is update - assignment change, promotion, etc. Is this possible with VBS business rules in