Eu tenho dois modelos da seguinte maneira:

class FlightSchedule(models.Model):
    tail_number = models.ForeignKey(TailNumber, null=False, blank=False)
    flight_number = models.CharField(max_length=30, null=False, blank=False)
    flight_group_code = models.ForeignKey(FlightGroup, null=False, blank=False)
    origin_port_code = models.ForeignKey(Port, null=False, related_name="Origin", blank=False)
    destination_port_code = models.ForeignKey(Port, null=False, related_name="Destination", blank=False)
    flight_departure_time = models.TimeField()
    start_date = models.DateField()
    end_date = models.DateField()

    def __unicode__(self):
        return u'%s' % self.flight_number

    class Meta:
        verbose_name_plural = "flights Schedule"


class PosFlightSchedule(models.Model):
    tail_number = models.ForeignKey(TailNumber, null=False, blank=False)
    pos_flight_number = models.ForeignKey(FlightSchedule, max_length=30, null=False, blank=False,
                                      related_name='pos_flight_number')
    pos_flight_departure_time = models.ForeignKey(FlightSchedule, max_length=30,
                                              related_name='pos_flight_departure_time')
    pos_route_id = models.ForeignKey(FlightScheduleDetail, null=False, blank=False, related_name='pos_route_id')
    pos_flight_date = models.ForeignKey(FlightScheduleDetail, null=False, blank=False, related_name='pos_flight_date')
    pax_count = models.IntegerField(null=True)

    def __unicode__(self):
        return u'%s' % self.pos_flight_number

    class Meta:
        verbose_name_plural = "Flights Schedule"

Para opos_flight_departure_time , Preciso das opções deflight_departure_time deFlightSchedule classe. Mas eu recebo oflight_number valores na lista suspensa. O que tenho que mudar para obter oflight_departure_time valores? As aulas são de diferentes aplicativos em um único projeto django. Então eles têm dois arquivos de administrador.