old_contents: from django.contrib import admin
  from django.db import models
  from django.forms.widgets import TextInput
  
  from treebeard.admin import TreeAdmin
  
  from abstract_models import AbstractSellingPoint
  
  
  class AbstractProductCategoryAdmin(admin.ModelAdmin):
      prepopulated_fields = {"slug": ("name",)}
  
  class AbstractNestedProductCategoryAdmin(TreeAdmin):
      prepopulated_fields = {"slug": ("name",)}
  
  class AbstractProductAdmin(admin.ModelAdmin):
      list_display = ['item_number', 'name',]
      prepopulated_fields = {"slug": ("name",)}
  
  class AbstractSellingPointAdmin(admin.ModelAdmin):
      """name your foreign key to product model "product" in order to fully utilize this class"""
      search_fields = ['text', 'product__name', 'product__item_number',]
      list_display = ['product', 'text',]
      formfield_overrides = {
          models.CharField: {'widget': TextInput(attrs={'size': '150'})},
      }
  
  class AbstractSellingPointInline(admin.StackedInline):
      extra = 0
      formfield_overrides = {
          models.CharField: {'widget': TextInput(attrs={'size': '150'})},
      }
  
  
new_contents: from django.contrib import admin
  from django.db import models
  from django.forms.widgets import TextInput
  
  from treebeard.admin import TreeAdmin
  
  from abstract_models import AbstractSellingPoint
  
  
  class AbstractProductCategoryAdmin(admin.ModelAdmin):
      prepopulated_fields = {"slug": ("name",)}
  
  class AbstractNestedProductCategoryAdmin(TreeAdmin):
      prepopulated_fields = {"slug": ("name",)}
  
  class AbstractProductAdmin(admin.ModelAdmin):
      list_display = ['item_number', 'name',]
      prepopulated_fields = {"slug": ("name",)}
  
  class AbstractSellingPointAdmin(admin.ModelAdmin):
      """name your foreign key to product model "product" in order to fully utilize this class"""
      search_fields = ['text', 'product__name', 'product__item_number',]
      list_display = ['product', 'text',]
      formfield_overrides = {
          models.CharField: {'widget': TextInput(attrs={'size': '150'})},
      }
  
  class AbstractSellingPointInline(admin.StackedInline):
      """set model=YourSellingPointModel in order to get this working"""
      extra = 0
      formfield_overrides = {
          models.CharField: {'widget': TextInput(attrs={'size': '150'})},
      }
  
  
subject: add docu to AbstractSellingPointInline