Need some help.

So I am planning on writing a fanfic where four people from a recently disbanded Familia join the Hestia Familia after the Apollo War game.

But I cannot figure out for the life of me what Rank it would put the familia at.

The new members joining would be two level 3's, one level 2 and one level 4.

I am not sure if this would even put them at C rank or just B rank....