Frappeclient's update method doesn't update child table

frappeclient’s update method doesn’t update child table Instead it’s removing the existing child table records on calling server.

Implementation Info:

from frappe import frappeclient

client = frappeclient.FrappeClient("hostname", "user", "pwd")
settings = frappe.get_doc("Custom Website Setting") # Single doctype.
client.update(settings.as_dict()) # it's overriding the existing child table records.

version-13(erpnext and frappe)