The Interline rates are available for the following:
Active employees (including employees of the National Air Traffic Controllers Association and the National Pilots Association), spouses, and parents (but not children) of CURRENT (not defunct) IATA/ARC appointed international, regional, commuter, or cargo airlines are eligible.
Retirees of such airlines also qualify on their own (but not their spouses, parents, children, widows/widowers).
Guests sharing accommodations with an eligible person also qualify. There is no limit to the number of cabins that can be used, but logically, the maximum possible would be four (employee, spouse, mother, father) for an active airline employee or a maximum of ONE for a retired airline employee
Dependent children of an eligible person that require an additional cabin are covered as long as they are travelling with the eligible person.
NB: At present Holland America interline rates are only available for residents of the US and Canada and interliners may have their bookings cancelled at short notice if there is a strong retail demand for a sailing.