If you need to save the pick information of an shipmnet/invoice then you can call the following using POST

<apiurl>/api/shipment/picks?supplieruid=&retailercode=&customercode=&ordernumber=&shipmentnumber=

Where

SupplierUid is your unique supplier id that can be obtained from our support crew

RetailerCode is the predefined retailer code that can be obtained from our support crew. Note this field is optional
CustomerCode is the customer code from you accounting system that the order was created with. Note this field is optional 

OrderNumber is the order number you want to save the picks for

ShipmentNumber is the shipment or invoice number you want to save the picks for

The body posted should be an array of picks as shown below

The call will return the following structure in  json. Status will either be success or error