old_contents: from django.contrib import admin
  from .models import Source, Registration
  
  
  class RegistrationAdmin(admin.ModelAdmin):
      list_display = [
          "id", "stage", "validated", "mother_id", "source",
          "created_at", "updated_at", "created_by", "updated_by"]
      list_filter = ["source", "validated", "created_at"]
      search_fields = ["mother_id", "to_addr"]
  
  admin.site.register(Source)
  admin.site.register(Registration, RegistrationAdmin)
  
new_contents: from django.contrib import admin
  from .models import Source, Registration, SubscriptionRequest
  
  
  class RegistrationAdmin(admin.ModelAdmin):
      list_display = [
          "id", "stage", "validated", "mother_id", "source",
          "created_at", "updated_at", "created_by", "updated_by"]
      list_filter = ["source", "validated", "created_at"]
      search_fields = ["mother_id", "to_addr"]
  
  
  class SubscriptionRequestAdmin(admin.ModelAdmin):
      list_display = [
          "id", "contact", "messageset", "next_sequence_number", "lang",
          "schedule", "created_at", "updated_at"]
      list_filter = ["messageset", "created_at"]
      search_fields = ["contact"]
  
  
  admin.site.register(Source)
  admin.site.register(Registration, RegistrationAdmin)
  admin.site.register(SubscriptionRequest, SubscriptionRequestAdmin)
  
subject: Add SubscriptionRequestAdmin - reviewed over shoulder by @gsvr