Anyway, my method isnt the most efficient and you end up with an extra account filled with level 60s of each class that may not be useful after RAF, unless you wanted to transfer any of them to other realms on one of your 5 accounts in the future... this gives you the option of being something besides a DK. Anyway, here's a quick outline of how to keep them all the same level:

Account M: Main (booster)
Account A: Refers Account B and Account C
Account X: Refers Account Y and Account Z

Group 1 uses accounts M, B, C, Y & Z. They get to level 60, then B&C grant A to level 59 and Y&Z grant X to level 59.
Repeat this process for a group each class (excluding DKs of course).

Pros to this method: No lost grantable levels this way. Each class has level 59s when they've completed. Easy to keep track of - Head doesn't hurt trying to figure out how to balance out all the levels.

Cons to this method: Not everyone gets a Zheva mount. Costs an extra $65 (Battlechest & a 60-day game card). You end up with the extra account of 60s (may or may not be a con). In your case it sounds as though you're going to have 7 accounts active during RAF since your booster isn't on the Vet account.