Trilogy box question

My friend for Christmas wants Factions/Nightfall ( I had an old Prop only account to let them try it out) So if they bought the trilogy box set, would it just add the F/NF to the account? Or would they have to start a new character because the trilogy key set up all three games and the old prop wouldn't add on to it?

It would be nice to just add the other 2, but then it would seem to waste a "prop" account, just giving it the Imp and MOX.

If you add the trilogy key to your current prophecies only account, it will just add on everything except prophecies. It would do nothing to your old account.

You also could try to shop around to get some good deals on the campaigns separately.

Here's the trilogy for $36.99 on amazon.

make a seperate account for the trilogy, turn the prof-only account into mule/trading(cheaper then buying a storage pane/more space)
Run gwx2 for easy transfering.

I'm assuming the issue he has is that his friend that he wants to buy the game for already has characters semi built up with what you can actually do on prophecies.
Remaking the new account and making that old one that had his friends previous hard work wouldnt really sound like an option, besides - Even if you do miss out on the prophecies, you still get the Imp and MOX, as you said