Though in any case, you'll want to at least RaF the two accounts from two different ones so you'll be getting triple xp on 4 chars instead of 3, so you can boost those 4 to 60 using your unlinked account. This way you'll get more teams (at least of 4) to 60 so you'll have more options later, and won't have to worry about trying to level a team of 5 with 3 of them getting triple xp and the other 2 not.