For active accounts, you have:
A > B
D > E > F

That's two RAF chains.

I would have your highest toon on "D".
And use D to boost A/B & E/F.

E gets RAF, because of their link to F.
Even though they don't fulfill RAF requirements with D/E, they do with E/F.





Personally, I would do your first set of RAF accounts.
And get every 5-box set you might want to play.

Once that is done, or the RAF runs out.
Then create a new 5-box RAF set, and level those.

I would chain the new set like this:
A > B > C
A > D > E

Then character transfer your 90 DK onto A.

Use A to boost BCDE.
If you boost 4x Shaman on BCDE, and then level a Shaman on A to 2nd level (almost 3rd).
You can give 39 granted levels from B to A (level 80 on B) and from D to A (level 80 on D), which adds up to a full 80 Shaman on A too.

If you use A to boost two sets of toons on BCDE.
C & E then have enough gained levels, to boost (from 2nd level) a free toon on B & D, respectively.

If you use A to boost four sets of toons on BCDE.
C/E each give two toons to B/D, who can each then give one toon (from 2nd) to A.
Plus B/D gave two toons each to A.
So you end up with four toons boosted on BCDE, two granted toons each on B/D and six granted toons on A.

Cascading granted levels is nice.