Collective invoice topic has been discussed many times but I didn't find exact solution to solve my issue.
From sap help and few other threads it is learnt that Billing type, Billing date, Payer, Billing unit, Terms of payment, Incoterms, Letter of credit should be same to have collective invoice. During my tests it is understood that apart from those Actual Goods Issue date (Post Goods Issue) date should be same to have collective invoice for different sales orders/deliveries. In my tests SAP didn't consider Billing date but it did consider Actual GI date. In other words, even the billing date and other requirements are same invoice split happend due to different Actual GI date. However collective invoice created even though the billing date is different but Actual GI date is same.
My user creates one sales order and one delivery for a customer once in a week (so 4 orders/deliveries in a month) and creates Invoice by end of the month with collective invoice. So based on the above tests I can ask the user to create sales orders, deliveries every week but perform Post Goods Issue month end and then create invoice so that collective invoice can be done. But the issue is they want to do the Post Goods Issue every week because the stock levels should reduce on weekly basis. So how can we create collective invoice even though the Post Goods Issue is done weekly (so Actual GI date will be different)
Any idea? Please let me know if further information required.