I would be wary about doing this to be honest...especially as you seem uncertain as to the purpose and what exactly is going to happen.

I once brought my husband to a session and that was okay, although I did feel embarrassed when my husband described how I was but I know it was helpful for my therapy at that time. Several years later and I was in crisis about 6 months ago. H called T and gave me the phone and I talked to her about what was going on between me and H. T then offered to talk to him for me and explain where I was coming from etc. It ended up with H talking to her for far longer than I did and getting very emotional and upset (because he never really talks to anyone about his feelings and finally had his chance and someone listening) and then when I finally got the phone back I very much felt like T was taking his side (because he is more expressive of his feelings and I am good at faking it and covering up). T asked me to look after him. I felt really betrayed and let down and like she had heard one thing from him and was already on his side. It ruined something between me and T and I would now never want to talk to her about my relationship problems. I really wish I had never done it.

I do admit however, that face to face it would have been different as we would have heard what each other was saying. That's just my experience but I would make sure you know what exactly is happening and be sure you are comfortable with it. Good luck