Nav5 one database two Groups seperate licence

I have a situation where we have an external group of 10 people and internal group using the same database, we have 50 licenses (perpetual) every now an then there are to many sessions open (all licenses taken).

The issue is the group of 10 must not be locked out, I’m not worried about the others.

Is it possible to assign 10 licenses to the individual 10?

Is it possible to split the license or better add a second license so you have 2 perpetual licenses, one for the internal users and one for the external users.

OK I’m out of Ideas.