I found that in the WIKI:

One existing account, 4 referrals [...]

2. Chain linking
X>A
A>B
B>C
C>D
Pros: Mounts on your first 4 accounts. You can use your main to boost. Main account gets mount. Levels are able to be granted to main.
Cons: ?

Is that true? I can use my main from account X to boost? I thought it is not possible since X is part of the RAF chain.
Thanks
Bal