having run into several of these-intentional or otherwise, I suggest the following:

Only if you are choosing from a small, like-named and easy to work with known pool of friends, might this work:

use first initial or consider a name that could be both male or female.

OR, when you tell your friend you are taking them, they need to kick in for that change fee cost too.

J or Jo smith could be John or Johanna, or Joanne, or Jason Osborne... etc...

Then, if possible, get other things (other plane tix, bus and train tickets, rental cars, etc) that have the name of the person to go with the ticket you already have. Then it will look like the airline made the mistake.

Now I recently ran into a situation where my friend made an honest mistake on this flight we both are booked on. He booked me as Jeff and my name is Jeffrey, and he booked himself as Harold and (long story) his full name is Hong Sik <lastname> (Asians do this type of thing sometimes for various understandable reasons).

The airline says they want a chance fee that's just way too stupidly high (think rip off!)

So he's since gotten a notarized leter from his employer saying Harold and Hong Sik are the same person (they really are) and he does happen to have 2 credit cards-each in each name, and he may do a quick name change thing in his state ($35 fee from the town hall?) and also, he has another airline ticket.

The flight in question leaves from LAX and goes overseas where this stuff really matters more. But he needs to get to LA and so his ticket from the east coast to LAX says:

Hong Sik Harold <lasname>.

I booked it using my miles for his ticket, and now he will have further proof he is indeed him.

Your situation is different and would have worked in the 80's, but unless you have a general idea of the people from which to choose, it is going to be tough. Better to book using miles and then pay the change fee that way. It is much easier. Or, ask this forum if anyone wants to go with you in return for something else later! who knows! Maybe I will!