schillingt provided the answer in the comments above. Here is what I ended up changing:
class FamilyMemberForm(forms.ModelForm):
def __init__(self, *args, **kwargs):
super(FamilyMemberForm, self).__init__(*args, **kwargs)
instance = kwargs.pop('instance', None)
if instance.is_staff:
self.fields["email_list"].queryset = EmailList.objects.filter(is_active=False)
else:
self.fields["email_list"].queryset = EmailList.objects.filter(is_active=True)
Of course, I will not be using the "is_active=False" and "is_active=True" in my actual query but it provided me a very quick way of testing my code.
Thanks!