from django.db import models


class First(models.Model):
    condition = models.BooleanField()


class Second(models.Model):
    pass


class BaseModel(models.Model):
    firsts = models.ManyToManyField(First)  
    seconds = models.ManyToManyField(Second)
    

class Third(models.Model):
    second = models.ForeignKey(Second, related_name='thirds')
    condition = models.BooleanField()