First, advise her to use plastic bags from the drycleaners when she packs evening wear. I had a long full skirt that I knew was going to be a mess once I unpacked. I put it in the plastic bag and was shocked how good it looked when I unpacked. So, using the plastic bag was all I did next cruise.
I had a gown pressed on another cruiseline and while the cost was not bad, I did not think they did such a great job. Gown came back with wrinkles.