You can't partially inherit but you can manually create the models with whatever fields you need. This is not exactly the same as multi-table inheritance but that is the only way to partially inherit fields:
class Base(models.Model):
force = fields.HTMLField(null=True, blank=True)
supermarket_planets = models.HTMLField(null=True, blank=True)
class Meta(object):
abstract = True
class ImYourFather(Base):
destroying_planets = models.HTMLField()
class Luke(Base):
# optional in case you need this
father = models.OneToOneField(ImYourFather, related_name='lukes')
the_cool_kid = models.HTMLField() # extra field added
edit
Another approach is to simply copy the fields from the father. This is all untested so Django might bark at you for some of it). The advantage is that no monkey-patching but should work:
exclude = ['id', 'destroying_planets']
try: # Django 1.7
fields = {i.attname: i.clone() for i in ImYourFather._meta.fields if not i.attname in exclude}
except AttributeError: # Django < 1.7
fields = {i.attname: deepcopy(i) for i in ImYourFather._meta.fields if not i.attname in exclude}
Base = type('Base', (models.Model,), fields)
class Luke(Base):
# optional in case you need this
father = models.OneToOneField(ImYourFather, related_name='lukes')
the_cool_kid = models.HTMLField() # extra field added