How to redirect request in A/B testing based on a particular parameter which has no fixed session or user. Eg. logistics

I want to incorporate A/B testing in courier service. So while sending goods there are api hits by different routing points, which are independent hit. Suppose A hits api1 which sit in M1 machine (old code) for sending a mobile. B hits api2 in M2 machine(new code) for receiving . New code in M2 expects a new parameter which old code in M1 doesnt send. There is a false failure here. What can be done?