How to Create Custom Sales Product

Situation:

You migrate data or delete product database, the button Add Custom Sale on POS will disappears. You need to recreate this product.

Edit file app/code/Magestore/Webpos/etc/adminhtml/menu.xml
Remove comment for this code

<add id="Magestore_Webpos::create_custom_sale" 
  title="Create Custom Sale" 
  module="Magestore_Webpos" 
  sortOrder="990" 
  parent="Magestore_Webpos::pos" 
  resource="Magestore_Webpos::pos" 
  action="webposadmin/index/createCustomSale"/>

Clear cache magento
Click menu pos -> Create Custom Sale