Do you want to play with your friend, or are you fine playing with five of your own characters/toons?

If you want to play with your friend (call their account A)...
You have A > B > C > D > E.
Play all five together, and ideally do a lot of combinations, as you never know what will be fun/strong down the road.

If you're not going to play with your friend often, or during the RAF process... but he has given you the referral...
Call him A again, and then your accounts are BCDEF.
We have A > B, which is the link from your friend to you.
And then you do two chains off of B.
B > C > D
B > E > F
Then you play BCDEF together, an initial group which you level to 85+
Then use the toon/character on B to 'boost' characters on CDEF.
B ends up with as many characters as they boost, because of doing two RAF chains from B and how levels cascade.



So the basic question is...
Are you going to be playing with your friend or have they given you a referral for the perks, but don't mind if you play on your own?