So yeah this is how you get more than one Deathknight on one realm
First, you need the free character transfers and then you transfer you Deathknight to the destination realm, once it is there make another deathknight on your mains server and transfer it to that server.
Rinse and Repeat
Proof:
<--Wants teh lose leacher
:wave:
ATTN: YES YOU CAN TRANSFER A DK TO A SERVER WITHOUT A 55 ON IT.
Still think im on a private server? Didn't think so.
=)