Must PTO continue to accrue during an FMLA absence?

Q: I have an exempt employee on FMLA who was out on leave for a month. Can we stop PTO from accruing while this employee is on leave? I have read the DOL regulations on this and it’s unclear. In addition, I contacted the Society for Human Resource Management (SHRM) and they said that if we allow the accrual of PTO for other employees taking other types of unpaid leave, we must allow an employee on FMLA to accrue also. Is the distinction "unpaid"? Because FMLA time can be paid. What about an employee who takes an unpaid vacation? Lastly, what if the employee comes back to work on a part-time basis for a few weeks? Can we allow only half PTO accrual? – Shanna, Florida