Filter get_search_results based on current object value and search term

Using Django The Admin
1

How do you filter autocomplete search results on an admin site based on one (or more) features entered on the current admin object?

In my case, I am designing a database of literary Works featuring their Authors and describing their excerpts (e.g., “Chapter 1” from Moby-Dick).

I want to filter the options for the Parent field of the Work model to only show works that share one (or more) authors with the Author already named on the admin page.

I can’t figure out why my current code (below) can’t retrieve the current author_id and filter works accordingly:

Relevant admin.py:

class WorkAdmin(admin.ModelAdmin):
    autocomplete_fields = [
        "author",
        "parent",
        "form",
        "genre",
    ]
    search_fields = [
        "title",
        "parent__title",
        "author__name",
    ]
    list_display = [
        "title",
        "author",
        "parent",
    ]
    list_filter = [
        "workinanthology__reviewed",
        "anthologies__series",
        "anthologies",
        "form",
    ]
    inlines = [
        WorkInAnthologyInline,
    ]

    def get_search_results(self, request, queryset, search_term):
        queryset, may_have_duplicates = super().get_search_results(
            request,
            queryset,
            search_term,
        )

        author_id = request.GET.get("author_id")

        if author_id:
            queryset = queryset.filter(author=author_id)

        return queryset, False

Relevant models.py:

class Work(models.Model):
    title = models.CharField(
        max_length=200,
    )

    author = models.ForeignKey(
        "Author",
        on_delete=models.SET_NULL,
        null=True,
    )

    parent = models.ForeignKey(
        "Work",
        null=True,
        on_delete=models.SET_NULL,
        blank=True,
        verbose_name="Parent work",
    )

    form = models.ManyToManyField(
        "Form",
        blank=True,
    )

    genre = models.ManyToManyField(
        "Genre",
        blank=True,
    )

    anthologies = models.ManyToManyField(
        "Anthology",
        through="WorkInAnthology",
    )

    is_editor_title = models.BooleanField(
        default=False,
        verbose_name="Was this work's title imposed by an editor?",
    )

    class Meta:
        unique_together = ("title", "author", "parent")
        ordering = ["-id"]

    def __str__(self):
        return self.title