I am looking for a way to use the onReceive() callbacks for up to three instances of a class, that each have a dedicated HardwareSerial attached to it.

onReceive() will only accept a static class member function, so it will be identical for all instances. I need to know which HardwareSerial called the callback to have the proper instance react accordingly.

Is there a way identifying the calling HardwareSerial while in the callback function? Or, alternatively, get notice about FIFO buffer full or FIFO timeout without the callbacks?