Oracle Drop Ship- What triggers customer invoicing?

Scenario: 

A drop ship PO is created for  1 SKU  

SKU1   =  100

The ASN is created for 75 .   

Our configuration is set to auto receive upon creation of ASN  

PO receipt is now saying   SKU1   Ordered 100     Qty Rcv'd  75

                                        

Will a customer invoice get triggered because the ASN was auto-received  for the 75 or will it wait until the line is fully received at 100?

IF a PO had multiple lines and only some were fully received via the ASN,  would invoicing still get triggered or would the system wait until the entire PO was fully received and generate only 1 invoice?

We have suppliers creating multiple ASN for the same vendor PO number.  It's being reported that the system is generating multiple customer invoices (one for each ASN).