Can't get to 8 for free with a team account :(

I don't know if this is a issue per se but i want to know if exist is the possibility to upgrade our free team account to 8 using the inviting people option that i get in my account.

We are 8 in our team and altought we can try with 5 our desire is to try with 8 until we pay the 10 person account.

Thx in advance.