Добавить в профиль пользователя ссылки на созданные им Activities (Админка Django)

class Activities(models.Model):
    activities_user = models.CharField(max_length=30)
    activities_name = models.CharField(max_length=40)
    activities_type = models.CharField(max_length=20)
    activities_start = models.DateTimeField(default=datetime.datetime.now())
    activities_end = models.DateTimeField(default=datetime.datetime.now())
    activities_duration = models.DurationField()
 
    def __str__(self):
        return self.activities_name

from django.contrib import admin
from django.contrib.auth.models import User
from django.contrib.auth.admin import UserAdmin
 
from appname.models import Activities
 
admin.site.unregister(User)
class UserActivitiesInline(admin.StackedInline):
    model = Activities
    fields = ('activity_link',)
    readonly_fields = fields
 
    def has_add_permission(self, request, obj=None):
        return False
 
    def has_delete_permission(self, request, obj=None):
        return False
 
    def activity_link(self, obj):
        return u'<a href="{0}">{1}</a>'.format(reverse('admin:appname_activities_change', args=(obj.pk,)), obj.activities_name)
    activity_link.allow_tags = True
    activity_link.short_description = Activities._meta.get_field('activities_name').verbose_name.title()
    activity_link.admin_order_field = 'activities_name'
 
@admin.register(User)
class UserProfileAdmin(UserAdmin):
    inlines = [ UserActivitiesInline ]