[Answer]-Override ForeignKey relationship in child model?

From what I read here, it is disallowed at present (and in django 1.7)

Field name “hiding” is not permitted¶

In normal Python class inheritance, it is permissible for a child
class to override any attribute from the parent class. In Django, this
is not permitted for attributes that are Field instances (at least,
not at the moment). If a base class has a field called author, you
cannot create another model field called author in any class that
inherits from that base class.

Overriding fields in a parent model leads to difficulties in areas
such as initializing new instances (specifying which field is being
initialized in Model.init) and serialization. These are features
which normal Python class inheritance doesn’t have to deal with in
quite the same way, so the difference between Django model inheritance
and Python class inheritance isn’t arbitrary.

This restriction only applies to attributes which are Field instances.
Normal Python attributes can be overridden if you wish. It also only
applies to the name of the attribute as Python sees it: if you are
manually specifying the database column name, you can have the same
column name appearing in both a child and an ancestor model for
multi-table inheritance (they are columns in two different database
tables).

Django will raise a FieldError if you override any model field in any
ancestor model.