Immediate fix? Don't leave the dogs alone on that trip and then train for the next trip.
I hope that answers the OP's question no matter how the question is interpreted to mean. GEEZ I was wrong thinking that part was obvious.
There are also many resources that the owners could utilize to start training immediately. That very trip. Actually, there would be no better time or place to start.
I have posted the basics of said training here many times.
Any professional dog trainer will tell you that in all reality, dog training is really the art of training the human owners. Most dogs are fairly easy to train, but the human owner....well that is another story.