How to access the vendor subsidiary relationship record in Suitescript?

HI There

For a suitescript creating a vendor record, how do you access the subsidiary list?

Use case:

A vendor record is created using parameters entered by the user (primary subsidiary; vendor name; category, email,etc) on a suitelet.

the subsidiary field on the suitelet is multi select.

All the subsidiaries selected need to be added to the vendor record.

Would you access the vendor's subsidiary list by using the 'subsidiary; sublist?

or would you create a vendor subsidiary relationship record after the record has been saved?

thanks