I opened a ticket with NetSuite support and they confirmed that it is not possible to set the shipaddresslist drop down with a Suitelet. It will always be set to 'Custom' if you try to set that field to the internal id of a saved customer address.

No, I'm telling you that this is not my concern. I am already sourcing the ship to drop down list into my Suitelet. What I'm unable to set is that same field on a sales order transaction from the Suitelet. I'm wondering if it is even possible. The shipaddresslist field always get set to custom regardless of what I set that…

I'm not having an issue setting the address fields. The fields on the address form are being set to the correct address. The thing I'm unable to set is the actual drop down with the internal id shipaddresslist. The suitelet is setting shipaddresslist to a certain internal id of a saved customer address and saving the…

Yes it is that drop down field, shipaddresslist, but no I'm not referring to showing it in the Suitelet. I'm talking about how to set that field on the sales order from a Suitelet that is creating a sales order. The Suitlet is showing the shipaddresslist drop down and getting the value from it and setting that on the sales…