custRecord.selectNewLine({
                                sublistId: 'creditcards'
                            });

                                custRecord.setCurrentSublistValue({
                                    sublistId: 'creditcards',
                                    fieldId: cc_key,
                                    value: cc_value
                                });

                            custRecord.commitLine({
                                sublistId: 'creditcards'
                            });