An existing account refers a new one.
That's always the process.

The existing account, might be brand new but it is configured and then sends an invite to the new account.

When two accounts, which are RAF linked:
a) Group together.
b) Are within a certain proximity to each other.
c) Are within +/- four levels of each other.
d) Kill mobs or complete quests which are not grey.
e) Are both level 59 or lower.
They get 300% experience, instead of 100%.

On a new server, with no characters, most would chain their RAF like this:
A > B > C > D > E

If you happen to have existing characters and decide to move to another server.
You could transfer your best tank, with a lot of gold to the new server and use them for boosting.
In this case, probably go like this:
A > B > C
A > D > E

Lots of options really.
Also note, even though A in the preceding example is an 80th.
B/C meet all the requirements for RAF (as does D/E) so they get triple, even though A/B and A/D do not meet the requirements....