Django + feincms. How to show self-formed list in admin interface?

Question

Django with FeinCMS can show anything from tables and it looks like nice. But what if I have to show some data which is not present in a certain table?

Here is my code:

##  models.py  ##
##  This is my main class.
class Application(models.Model):
    name = models.CharField(max_length=100)
    category = TreeForeignKey('Category', blank=False, null=False, verbose_name="name")
    ....

    class Meta:
        ordering = ('category__tree_id', 'category__lft', 'name')

##  This is my category class.
class Category(MPTTModel):
    name = models.CharField(max_length=50, unique = True)
    parent = TreeForeignKey('self', blank=True, null=True, related_name='children')

    class MPTTMeta:
        include_self = False
        order_insertion_by = ['name',]
        ordering = ['tree_id', 'lft']

##  This function returns list that I need to show in admin interface. As you can see I have to show name of every object which belongs to category.

    def get_trailer(self):
        application = Application()
        apps_list =  [application.__unicode__() for application in Application.objects.filter(category=self.id)]
        logging.error("This is apps_list from get_trailer!")
        logging.error(apps_list)
        return apps_list

##   Registering Category model as MPTT.
mptt.register(Category, order_insertion_by=['name'])

Here we got code of admin interface:

##  admin.py  ##
##  This is class for show Application.
class ApplicationAdmin(admin.ModelAdmin):
    list_display = ('name', 'category')
    list_filter = ('category',)
    ordering = ('category__lft',)

##  This is class for show Category.
class CategoryAdmin(tree_editor.TreeEditor):
    list_display = ('name', 'id',)
    list_filter = ('parent',)
    ordering = ('category__lft',)

Ok. Here we get all categories in tree-like format. When we click in any category we see just its name and parent. Look at this screenshot:

So, how to show this list through django and feincms? I don't want to create new keys in tables to do it.