Add Trilogy to GOTY?

I currently have the GOTY version and my son wants to buy some expansions. We were thinking of getting the Trilogy - so that:

A: we would get 2 expansions plus EOTN with the current promotion
and
B: that we would have 2 copies of prophecies to be able to play at the same time.

But as we got to thinking about it we didn't know if the digital download version would have a separate key for each expansion and prophecies, or if it would be one all encompassing key. Our dilemma is that we want to keep our current characters and 2 copies of prophecies (so we would have 2 accounts - the old one with the new expansions, and a new prophecies).

Am I making sense? and does anyone have the answer? This is going to be my xmas present, so time is of the essence.

Thanks

The trilogy + EOTN will be different digital keys if you buy it on two different account, if that's what your question is asking.

I am in the same situation. I am wanting to know if I add the trilogy on top of my current prophecies account if I will then get 2 separate prophecies copies so I can add the extra one to make a 2nd account.

i would imagine u get a key for each expansion like u do when trading in regular shops....so u can add the key for a certain expansion to any account u wish.

It is my understanding the Trilogy only has one key. If you add this to your GOTY edition you will still only have one Prophecies account, along with Factions and Nightfall, but you won'y lose anything from your original account (characters, /bonus weapons etc). Features will not be duplicated.

I am not sure how EotN is added if you buy it through the current promotion, either as part of the trilogy key, or as its own separate key. I'm guessing the former

You can choose to create a new account with the trilogy, in which case you cannot use your pre-existing GotY characters in your new account. In that case you'd have 2 prophecies.

To add to the above, The trilogy only has one key. In this case the EotN may have a separate key, but maybe not, they may just use a key from the Euro Collection (which is all 3 campaigns + EotN).
As Hollygen said, if you add the key(s) to your existing account, you will not get 2 copies of Prophecies. The closest you could get would be to start a new account with the Trilogy key (if possible - see below). Then you would have a new account with all campaigns and the old account with just Prophecies.
Note: if you buy the Trilogy through the on-line store, the keys will be automatically added to the account that is logged into the store.
(I'm not sure what happens if you buy the game through the PlayNC site.)