[Django]-Add fields in admin.py from a ManyToMany

class ReplyAdmin(admin.ModelAdmin):
    list_display = ["__str__", "user", "question", "creationDate", "get_pages",]

    def get_pages(self, obj):
        return "\n".join([page.title for page in obj.question.page.all()])

    class Meta:
        model = Reply   
admin.site.register(Reply, ReplyAdmin)