Partial posting packing slip using X++

I found the snippet code that post the packing slip using X++ using SalesFormLetter shown below.

However, I would like to partially post the packing slip ( i.e. not fully packed/delivered ).

How could I modify the code in order to do that ?

SalesFormLetter salesFormLetter;
salesTable salesTable;

salesTable = SalesTable::find(‘SO-000000175’);

salesFormLetter = SalesFormLetter::construct(
DocumentStatus::PackingSlip);

salesFormLetter.update(
salesTable,
systemDateGet(),
SalesUpdate::All,
AccountOrder::None,
NoYes::No,
NoYes::Yes);