Concurrent FMLA and PTO in same pay period

Summary

FMLA and PTO are both reducing salary causing negative pay

Content

When we put a salaried employee on approved FMLA, absence sends info to payroll and payroll reduces salary for 80 hours.  We pay an employee their PTO at the beginning of their leave.  We need this time to count against FMLA time, so we use concurrent leave plans.  For PTO, absence also tells payroll to reduce salary for the number of PTO hours.

What is happening (example, FMLA of 80 hours, and PTO payout of 40 hrs)

Payroll is reducing salary by 120 hours (80 FMLA hours + 40 PTO hours), and paying 40 PTO hours.  This is resulting in negative pay and we cannot pay the employee.