Export under gst

1. Yes you can raise only one invoice.

2. Under mudule SKD/CKD

For the purpose of movement of goods which are under SKD / CKD condition, the supplier needs to follow the below procedure
Raise a single invoice for the supply of goods, though getting transported via different vehicles
Raise delivery challan for each of the vehicles drawing reference to the invoice number (same for all the delivery challans)
Each Vehicle to carry delivery challan along with the certified copy of the invoice
Eway bill to be generated for every delivery challan generated for different vehicles
Original invoice to be sent along with the last consignment