When SPS Commerce is sending the request without order line attribute to create item fulfillment, it works. But when I am trying that same payload, it is throwing an error that I need to specify the order line.

Item fulfillment records are created from sales orders or transfer orders and all order lines that are fulfillable are brought in as part of the dataset.

I know that. The problem is the XML they are sending works fine. If I use it, it throws an error about order line.

what does their request look like