I have this Page with a ForeignKey districtobject:

class DistrictPage(Page):

    districtobject = models.ForeignKey(DistrictTranslated, on_delete=models.SET_NULL, null=True, blank=True)
    streamfield  = StreamField(BasicStreamBlock, null=True, blank=True, use_json_field=True)

    content_panels = Page.content_panels + [
        #InfoPanel(),
        FieldPanel('districtobject', classname="full"),
        FieldPanel('streamfield'),

    ]

In the wagtail admin interface the dropdown menu have to much values for districtobject. I want to implement a dynamic filter, which shows only a few entries based on the parent Page object.

How/where can I implement my own queryset for this dropdown?