I (sort of) asked this question when booking my cruise. One of the groups going with us needed to know if need be could ONE of her passengers be changed to a different person. The answer was as long as the LEAD person stayed the same, you could change the other people, but not add people. You cannot take the lead person off your reservation - they will treat this as a cancellation. Since your friends would have to have the documents in their names, it sounds like from the information I was told that your answer would be no. In case you're wondering I'm booked through Dreams Unlimited so that's where I heard it from.
GET UP TO A $1000 SHIPBOARD CREDIT AND AN EXCLUSIVE GIFT!
If you make your Disney Cruise Line reservation with Dreams Unlimited Travel you’ll receive these incredible shipboard credits to spend on your cruise!