What you have to keep in mind is the linked account can only give levels to the account that referred it. If you want to give each account free levels then you'll need to refer one account, upgrade it, use it to refer another and so on (last one won't get free levels of course).

If you use your vetran account to refer 4 other accounts only the vetran account will get the free levels.

Another thing to note, if you refer using your vetran account you cant use a 70 on that account to boost (although this feature will be 'fixed' in the future its still active as of sunday night).

I'm guessing you dont want 2 druids on the same account, I would personally use Account 1 to refer account 2, upgrade account 2 and use it to refer account 3 and so on, this gives you 4 accounts that can recieve gift levels and should you ever decide you want to just level 2 characters you can still take advantage of the 3x xp.