An invoice is automatically filled with Shop-Script products if the invoice deal is linked to an order.
You can also manually add any products from Shop-Script catalog to a CRM invoice. For instance, when you need to change an automatically filled invoice or if an invoice deal is not linked to a Shop-Script order.
Start typing a product name in “Product or service” column, and live search will show you matching items. Select the desired one to add it to your invoice.