Deficiency from surrendering underwater home

[greenthinker]

Our plan was recently modified to surrender our home, which is about $100K underwater. I asked our attorney at the time if we would be responsible for the deficiency (i.e. the lender filing an unsecured claim, which we would have to pay because we're in a 100% plan), and he said no. But, I just reread the modified plan, and it does not address the subject of a deficiency at all, so I'm wondering if that ambiguity will be a problem. Any thoughts? Thanks!