ABC cannot force epployee to come work and if employee is out of work under valid FMLA time, ABC cannot fire them or penalize them for not coming to work. ABC cannot make XYZ allow employee to work under the contract so, where does that leave employee?
If ABC has other work, then there but ABC is not required to displace another worker to make room for employee.
I suspect ABC is telling employee they need to do whatever it takes to come to work if they expect to remain performing services for XYZ. I do not believe they are actually ordering employee to report to work in violation of the FMLA.

