A (Booster)

Links:
A -- B -- C
A -- D -- E

This will work great.
You have two sets of links, each two links deep.
So you will ideally boost 4 or 8 toons on BCDE with A.

Because of the two links in the chain, 4 levels results in a full character on A based on granting levels from levels received from grants.
IE, C/E each give B/D two toons. These two toons on B/D can combine to give A a full toon.

B/C and D/E each give the other a valid RAF link.
So A can boost away, and BCDE each get the RAF bonus.