How to set permissions on child doctypes?

I noticed that we cannot add permissions on Child Doctypes in ERP Next by going to the permission manager. Is there any other way of doing it like using a script? I tried the following in the picture but I’m getting this error “TypeError: ‘NoneType’ object is not callable”

Below is my code and the error is coming from line 19

Is Dependants a child table linked with doctype Member?

Yes exactly

ok…you can modify my code for your requirements.
dependent_list is field name for Dependant child table in doctype Patient.

import frappe
import json
from frappe.utils import cstr

def gen_response(status,message,data=[]):
	frappe.response['status_code'] = status
	frappe.response['message'] = message
	frappe.response['data'] = data

def update_patient_dependent(patient,dependent_list):
		data = json.loads(patient)
		if not data.get("name"):
			gen_response(400, "Insufficient Param Passed")
		elif not frappe.db.exists("Patient", data.get("name")):
			gen_response(404, "Invalid Patient ID")
			doc = frappe.get_doc("Patient", data.get("name"))
			if dependent_list:
				doc.dependent_list = []
				for dependent_list in json.loads(dependent_list):
					{"relative_name" : dependent_list.get('relative_name'),
					"relation" : dependent_list.get('relation'),
					"description" : dependent_list.get('description'),
					"mobile" : dependent_list.get('mobile')}
			gen_response(200, "Patient Dependent Updated Successfully")

	except frappe.MandatoryError as e:
		doc = frappe.new_doc("Patient")
		mandatory_fields = e.args[0].split(':')[1].split(',')
		mandatory_fields = [doc.meta.get_label(
			field.strip()) for field in mandatory_fields]
		message = "Could not update Patient due to the following missing mandatory field(s):" + \
			" "
		message += "" + ",".join(mandatory_fields)
		gen_response(500, message)
	except frappe.PermissionError as e:
		gen_response(403, "Not Permitted")
	except Exception as e:
		gen_response(500, cstr(e))

Thanks very much, it worked