Ability to clash sick leave with other leave requests

We have an employee who recently needed to report a sick request on a week where they had already booked leave to display working from home, and due to the clashes being blocked, they were unable to do this right away without a manager approving the cancellation of the pre-existing leave request. 

Unfortunately this procedure was quite exhausting for someone who was taking the time off unwell, it would be much easier for us if the sickness report can override the Working From Home request.