How do you get a separate asset to create from the interface from AP with a multiple quantity PO lin

When we are invoiced for 1 qty, from a 2 qty PO line and we interface the voucher over to AM we consolidate it with additional lines to create one asset.  Later we are invoiced for the 2nd quantity, we want the 2nd line to be consolidate also but it comes over as an ADQ line and not an ADD.  What might be missing in set up or options available to make sure the additional quantity creates a new asset?