Have you tried calling the cruise line or your travel agent? How long ago did you book? Were you originally booked under a "Guarantee"? When made the booking your sister's and your booking should have been linked. That doesn't guarantee you will be by each other though. It sounds like you may have booked under the "guarantee", which you are subject to the cabins they select. You can always ask if they can get you closer together. However; this close to the cruise it may be difficult. For best cabin selection Alaska cruises are booked a year or more in advance. I would just call whomever you booked with and see if you can't get cabins closer to each other.
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