Hi all - any tips on migrating part billed sales orders from one instance of netsuite to another?

there are two methodologies in doing this: 1) do remaining balance or 2) do the entire order. each way has its advantages/disadvantages. with the second method you also need to upload posted invoices and payments and post and reverse revenue journals, but the upside is you keep your whole contracts

Thank you @Karina With the second method, do you mean transform or create invoices from the migrated sales orders because if I recall correctly, you can't link an uploaded invoice back to a sales order?

correct, invoices are not going to be linked to SO unfortunately if uploaded, that is another consideration to have. I rarely (more like never in the end) see the full order migration, mostly due to huge undertaking in analysis and data validation

as @Karina said you usually do this via script etc.