Each toon gets to grant levels, based on what they earnt.

The current scheme is one level granted per even level gained.
So a toon who leveled from 1st to 60th, can grant 30 levels.
Or a DK who leveled from 55th to 60th can grant 3 levels.

You can grant levels to toons who are lower level then yourself.
But only to toons of level 59 or lower.
If you're 60th, then the second restriction is the only limiter.
If your toon is 26th, you can only grant levels to 25th or lower level toons.

Then A >> B is an account reference, as far as the linking goes.
But it is the toon who earnt levels that actually does the granting.






*Edit*

If E grants 10 levels to D.
A level 20 becomes a level 30.

The level 30 on D, can now grant levels to C.
They can grant a total of 5 levels (22, 24, 26, 28, 30), to toons of levels 29 or lower.

C will in turn be able to grant levels to toons on B.
But it will be reduced again.