Sacred Haven of Debauchery

I'll create a character with 10 charisma and play. I'll take bonuses for it later. By the way, does anyone remember how high charisma can be increased? If, for example, I upgrade it to 10, then get a +1 operation, and then take a +1 skill, will that total of 12 allow me to take another companion, or not? I also remember there was a skill called "Charm" that automatically allows you to take one extra companion.