Hi Tomasz,

In order to migrate the customer order and order lines, simply you can create two sauce migration jobs  (literally there will be four jobs 2 to import legacy data and 2 to migrate data using those imported data).

1st create a migration job to import the customer order header information  , use the “Create table from file” procedure for this and use the “CUSTOMER_ORDER”. 

the create the another migration job using the procedure  “Migrate Source data” and do the necessary mappings and run the migration 

follow the same procedure for customer order line and you can use the view “CUSTOMER_ORDER_LINE”

for more info refer the ifs docs.

Kind Regards!
Niyomal.