How to redefine a property in the heir?

Question

Python

Can anyone explain how this is resolved?
Why does saving work in the child method, but the value of the parent remains in the content property?
And is it possible to somehow override the property?

from django.db import models

class Father(models.Model):
    COST = 100
    content = models.TextField(max_length=COST)

    class Meta:
        abstract = True

    def save(self, *args, **kwargs):
        if self.COST > 200:
            self.action = True
        super(Father, self).save(*args, **kwargs)

class Children(Father):
    COST = 500
    action = models.BooleanField(default=False)

Answer 1

try declaring the action field in the parent class:

class Father(models.Model):
    COST = 100
    content = models.TextField(max_length=COST)
    action = models.BooleanField(default=False)

    class Meta:
        abstract = True

    def save(self, *args, **kwargs):
        if self.COST > 200:
            self.action = True
        super(Father, self).save(*args, **kwargs)

class Children(Father):
    COST = 500

Answer 2

Try:

class Children(Father):
    COST = 500
    action = models.BooleanField(default=False)

    class Meta:
        content = models.TextField(max_length=COST)

or

class Father(models.Model):
    COST = 100
    content = models.TextField(max_length=self.COST)
...