admin.py

from django.contrib import admin
from .models import Gallery, Image


class ImageInline(admin.StackedInline):
    model = Image
    extra = 0
    fields = ('image',)


class GalleryAdmin(admin.ModelAdmin):
    inlines = (ImageInline,)

admin.site.register(Gallery, GalleryAdmin)

models.py

from django.db import models
from filer.fields.image import FilerImageField

class Image(models.Model):
    gallery = models.ForeignKey('Gallery')
    image = FilerImageField(verbose_name=u'Imagem')

class Gallery(models.Model):
    title = models.CharField(u'Título', max_length=65)