[Answered ]-How to make models connected via ManyToMany relationship editable in two places at the same time in Django admin?

I am not sure that it can meet your needs but i’ve done something similar by using TabularInline. Somethink like this should work (i didn’t test the following code).

class Subject(models.Model):
    ...

class News(models.Model):
    subject = models.ManyToManyField(Subject, through="NewsSubject")

class NewsSubject(models.Model):
    news = models.ForeignKey(News)
    subject = models.ForeignKey(Subject)  

class NewsOfSubjectInline(admin.TabularInline):
    model = NewsSubject
    raw_id_fields = ('news',)

class SubjectAdmin(admin.ModelAdmin):
    inlines = [NewsOfSubjectInline,]

class SubjectOfNewsInline(admin.TabularInline):
    model = NewsSubject
    raw_id_fields = ('subject',)

class NewsAdmin(admin.ModelAdmin):
    inlines = [SubjectOfNewsInline,]