If you only wish to display the assets of an employee, you could change the default django admin change_form.html. (and you may also want to disable the inline first)
To override the default admin templates, copy the admin template folder to your local django template folder(the ${TEMPLATE_DIRS} in your setting.py)
And in change_form.html, there is this block,
{% for inline_admin_formset in inline_admin_formsets %}
{% include inline_admin_formset.opts.template %}
{% endfor %}
Which is used to display the inlines, and what you can do here is, rendering some extra information, such as a list of assets of current employee, to this template, and place them above where the original position of inlines.
And now the question is: how do I render this extra information to this template? This can be done by overriding the change_view() function in your Employee's admin model.
For example, in your admin.py
class EmployeeAdmin(admin.ModelAdmin):
...
def change_view(self, request, object_id, extra_context=None):
assets = Asset.objects.filter(employee=Employee.objects.get(id=object_id))
context_data = {'inlines': assets, }
return super(EmployeeAdmin, self).change_view(request, object_id, extra_context=context_data)
And now back to your admin's change_form.html, user the template tags to display the extra_context from your EmployeeAdmin.
for example,
{% for inline in inlines %}
{{ inline }}
{% endfor %}
{% for inline_admin_formset in inline_admin_formsets %}
{% include inline_admin_formset.opts.template %}
{% endfor %}
Hope this helps, and this is with django 1.2.4