We have some customers that come by our sales counter and only pick up a small amount of material that by itself is not worth the cost of the invoicing process, so we hold it and every time they come by we keep adding to the same “hold” sales order until one of two things happen:
- The amount is large enough to be invoiced
- The month ends (now considered a monthly billing)
These customers could be handled the same way. You could allocate items to an order and have new pick tickets only include un-allocated (shipped) items for future additions. This would show the inventory as allocated – not available. You could alternatively use the Periodic (monthly) billing feature where you invoice as they pick up but only send a monthly invoice summary of what they purchased throughout the month.