Salary slip from timesheets with multiple activity costs

I have employee that has two separate activity costs during the week. The timesheets reflect the shifting rates of the activity costs. When I create a salary slip from those time sheets, the salary slip defaults to the rate in the salary structure and ignores the actual shifting activity costs in the timesheets. Is there a way to have the Salary Slip follow the rate from multiple activity costs in the timesheets?

If there is not a way, then how to account for multiple activity costs for 1 employee?

Thank you