Contract Labor

Though the question is vague, if what you're asking is whether a current employee who temporarily also re-assumes prior duties can be paid for that work as a contractor, though it's mixed in the same work schedule/work week as the current duties, the answer generally is no. As her employer, you can direct her to do any duties and change those duties, and the short-term addition of new/resumed additional duties doesn't give you any way to avoid the overtime provisions of the Fair Labor Standards Act. You can, under the FLSA, sometimes enter into a specific agreement with an employee concerning compensation that will protect you, but not in the scenario you're describing, where it's just a shift in duties during the work day.