one issue I think I see with this.. correct me if I'm wrong:

The way you have it planned out, you'll have all your grantable levels cascading back toward one veteran account, so you'll easily get that veteran 40 to lvl 60. However, you won't have any ability to grant levels to your other 4 veteran accounts, so you'll end up with 6 accounts with at least 1 60, and 4 veteran accounts that could not get any grantable levels, so didn't advance to 60.

You definately get more grantable levels, and thus more free 60s by cascading the referred accounts the way you have mapped out, but if your main goal is to have 10 toons levelled simultaneously to 60->70->80, and plan to level each team of 5 as a core unit, by grinding/questing, maybe it would be better to have each veteran acct refer 1 new acct, and use the new accts to boost the veteran accts up to 60 --- just accepting that you'll have fewer free levels to give out.

One additional draw-back to my proposal is you won't be able to cascade summons thru the game.. e.e. A summons B, who summons C, etc..