Конечно.
class BlogForm(forms.ModelForm):
entries = forms.ModelMultipleChoiceField(
queryset=Entry.objects.all(),
widget=forms.CheckboxSelectMultiple)
class Meta:
model = Blog
def __init__(self, *args, **kwargs):
super(BlogForm, self).__init__(*args, **kwargs)
if self.instance:
entries = Entry.objects.filter(blog=blog)
self.fields['entries'].queryset = entries