Partial invoicing of lot tracked sales order lines.

In this scenario the Sales Order is shipped at once, but sales invoicing is done in chunks following the shipment.

Posting fails because the Item Tracking Line does not set Qty. to Invoice (Base) and indirectly Qty to Invoice fields, according to the Qty to Invoice field as on the Sales Order.

This causes an error message: "The quantity to invoice does not match the quantity defined in item tracking." when attempting to post an invoice from the order.

While manually setting the the Qty. to Invoice (Base) on the item Tracking Lines according to that on the PO line resolves the matter, I have some questions for discussion.

1. Is this is the correct approach, and shouldn't the system rather set the Qty to Invoice in the tracking lines automatically? One may reason that the system will not know which lot's tracking line to update (if more than one lot / tracking line is used for the same Order line). Since invoicing is about financial value of inventory, I do not think which lot matters at all. Except perhaps if the costing method is 'Specific'. Hence does it really make sence to manage Quantity to Invoice on Item tracking lines at all?

2. Will partial invoicing in this fashion adversely affect inventory costing? Average costing I believe (without checking), affects costing according to oldest open Item Ledger Entry first - i.e. regardless of lot thereof. Same for FIFO. Is this correct?

To put it differently, will COGS be affected and the open item ledger entry be closed off (applied) according to the actual lot selected or according to the oldest open ILE regardless of the Lot?

Thanks