Django model relationship infos with on_delete property

I want to know what models are children of a model with on_delete property. As I know like below if we have ownerModel which is parent of childModel1 and check1Model:

import uuid
from django.db import models

class ownerModel(models.Model):
    ownerId = models.UUIDField(default=uuid.uuid4, unique=True, primary_key=True, editable=False, blank=True)

class check1Model(models.Model):
    checkId = models.UUIDField(default=uuid.uuid4, unique=True, primary_key=True, editable=False, blank=True)
    owner=models.ForeignKey(ownerModel,on_delete=models.CASCADE)

class childModel1(models.Model):
    childId = models.UUIDField(default=uuid.uuid4, unique=True, primary_key=True, editable=False, blank=True)
    check2=models.ForeignKey(ownerModel,on_delete=models.CASCADE)

then we can get what models are children of ownerModel with a code like this:

class myView(views.APIView):
    def get(self, request, format=None):
        for f in ownerModel._meta.get_fields():
            if 'field' in f.__dict__.keys():
                print('***childModels***')
                print(f.__dict__)
                print()
        return Response({'0000'}, status=status.HTTP_200_OK)

I mean by checking if the field key is in __dict__.keys() in items of ownerModel._meta.get_fields()

ofc so like here we get extended info about children models:

***childModels***
{'field': <django.db.models.fields.related.ForeignKey: owner>, 'model': <class 'Users.models.ownerModel'>, 'related_name': None, 'related_query_name': None, 'limit_choices_to': {}, 'parent_link': False, 'on_delete': <function 
CASCADE at 0x00000286550848B0>, 'symmetrical': False, 'multiple': True, 'field_name': 'ownerId', 'related_model': <class 'Users.models.check1Model'>, 'hidden': False}

***childModels***
{'field': <django.db.models.fields.related.ForeignKey: check2>, 'model': <class 'Users.models.ownerModel'>, 'related_name': None, 'related_query_name': None, 'limit_choices_to': {}, 'parent_link': False, 'on_delete': <function CASCADE at 0x00000286550848B0>, 'symmetrical': False, 'multiple': True, 'field_name': 'ownerId', 'related_model': <class 'Users.models.childModel1'>, 'hidden': False}

so I find these 2 conditions necessary to get child models info:

1. in child models making sure child relationship is set up with a line like line below:

models.ForeignKey(ownerModel,on_delete=models.CASCADE)

2. as said "if the field key is in __dict__.keys() in items of ownerModel._meta.get_fields()" to get children info.

but the problem is that in some cases I can't get the children info from parent model. so:

1. it makes me wonder if are these 2 conditions are enough to find out which models are children of a model or not?

2. are there other similar ways to get which models are children of a model?

btw I want to have on_delete also and having on_delete is the only reason I am using _meta.get_fields() over _meta.fields because _meta.fields doesn't provide on_delete property.