From the FedEx shipping guide:
14.1 FedEx reserves the right to route the Shipment in any way it deems appropriate. There are no transit places, which are agreed upon at the time of tender of the Shipment. FedEx assumes no obligation to reroute any Shipment to a third country or carry the Shipment by any specified aircraft or over any particular route or to make connection at any point according to any schedules. FedEx may, without notice, substitute alternate carrier or aircraft, deviate from the route or routes, or cause the Shipment to be transported by motor vehicle. The Sender agrees to FedEx's right to divert any Shipment (including use of other carriers) in order to facilitate its delivery.
Doesn't matter which opco you choose as long as the service commitment is met for the agreed upon price.