in django i report progenitor child saved unfamiliar pivotal relationship?

i have following twin models:

class activity(models.model):
    name = models.charfield(max_length=50, help_text='some help.')
    entity = models.foreignkey(cancellationentity)
    ...


class cancellation(models.model):
    activity = models.foreignkey(activity)
    date = models.datefield(default=datetime.now().date())
    outline = models.charfield(max_length=250)
    ...

i activity denote wakeful termination associated saved (both extrinsic updated).

what best proceed this?