Django admin: Inline straight to second-level relationship

I think your problem could be solved using the ManyToManyField + through. (This is an example)

#models.pyclass Invoice(models.Model):    full_total = DecimalField(...)    # has a .sub_invoices RelatedManager through a backref from SubInvoiceclass SubInvoice(models.Model):    sub_total = DecimalField(...)    invoice = ManyToManyField(        'server.Invoice',        through='server.InvoiceItem',        through_fields=('sub_invoice', 'invoice'))    # has an .items RelatedManager through a backref from InvoiceItemclass InvoiceItem(models.Model):    sub_invoice = ForeignKey('server.SubInvoice')    invoice = ForeignKey('server.Invoice')    product = ForeignKey('server.Product', related_name='+')    quantity = PositiveIntegerField(...)    price = DecimalField(...)#admin.pyfrom django.contrib import adminfrom .models import InvoiceItem, Invoice, SubInvoiceclass InvoiceItemInline(admin.TabularInline):    model = InvoiceItem    extra = 1class InvoiceAdmin(admin.ModelAdmin):    inlines = (InvoiceItemInline,)admin.site.register(Invoice, InvoiceAdmin)admin.site.register(SubInvoice, InvoiceAdmin)

I would recommend working with classes for this one in your views.py and use inlineformset_factory in your forms.py for this.Using jquery-formset library in your frontend as well, as this looks pretty neat together.

NOTE:You can also use on_delete=models.CASCADE if you want in the InvoiceItem on the foreignkeys, so if one of those items is deleted, then the InvoiceItem will be deleted too, or models.SET_NULL, whichever you prefer.

Hope this might help you out.