You got to get your B spec level to level 5 to add another driver.
Partially wrong...
It takes to level 10 before being able to create multiple B-Spec drivers.
Furthermore in the game it's expected to be races with multiple B-Spec drivers required, possibly Endurance races.
I'm confused. Do I have to be level 5 or 10 in order to add a secondary driver for my B-Spec events.
No. I believe the only races where you can use 2 or more drivers in are the endurance series. I have not come across such a race and I am at expert races.You can hire a second B-Spec driver at level 5 i believe and 10+ you can then race 2 or more drivers as you rank up.