Hello everyone, I'm just wondering how do you unlock new party slots? I'm asking because my current quest I'm on is a two on one battle. I'm just wondering do I need to be a particular level or do I have to buy an extra party slot. Hope you can help me soon. Thank You.

I don't believe that this thread is in the right place but I will answer the question anyway.
When you reach the Umbra Forest in the Sanctuary of Saerielle you can increase you party size to three. I do believe it costs money but I don't remember how much money.