How do I override an admin template (e.g. admin/index.html) while at the same time extending it (see https://docs.djangoproject.com/en/dev/ref/contrib/admin/#overriding-vs-r
The best way to do it is to put the Django admin templates inside your project. So your templates would be in templates/admin while the stock Django admin templates would be in say template/django_admin. Then, you can do something like the following:
templates/admin/change_form.html
{% extends 'django_admin/change_form.html' %}
Your stuff here
If you're worried about keeping the stock templates up to date, you can include them with svn externals or similar.