Fulfill Partial Shipment in API

[GeorgeDuthie]

I am trying to partially fulfill a test order, but all the lines are being fulfilled. Am I doing something wrong?

I'm sending a post request to https://[site].myshopify.com/admin/api/2021-04/orders/[order number]/fulfillments.json
with a JSON of
{
"fulfillment": {
"location_id": [shop location id]
,"tracking_numbers": ["1Z6A3Y98030000ABCD"]
,"tracking_company": "UPS"
,"notify_customer": true
,"Line_items": [{"id": [line item id],"quantity": 0 },{"id": [line item id],"quantity": 1 },{"id": [line item id],"quantity": 1 }]
}
}

Thanks 

George