N/record Module
Record.insertLine()
Method Description: Inserts a sublist line. When you insert a line with this method, all succeeding lines are moved and the total line count is increased. Essentially, succeeding lines are committed to a new sublist line with a new line number. (dynamic and standard mode — see SuiteScript 2.0 – Standard and Dynamic Modes)
Returns: record.Record
Supported Script Types: Client and server-side scripts For more information, see SuiteScript 2.0 Script Types.
Governance: None
Module: N/record Module
Sibling Object Members: Record Object Members
Since: 2015.2
Search NetSuite - https://system.netsuite.com/app/help/helpcenter.nl?search=Record.insertLine(options)

// Code Example 1

// Add additional code.

//...

objRecord.insertLine({

    sublistId: 'attendee',

    line: 2,

   });

objRecord.setCurrentSublistValue({

    sublistId: 'attendee',

    fieldId: 'attendee',

    value: 838

   });

objRecord.commitLine({

    sublistId: 'attendee'

   });

//...

// Add additional code.



//SOURCE: https://system.netsuite.com/app/help/helpcenter.nl?fid=section_4273158210.html