You are going to have to review the court case cited in the answer along with link in my last comment. Basically your original half basis will stay the same, the stepped up basis on the other half will increase to FMV and would have no accumulated deprecation on it. Best advice is to get a sheet of paper and lay this all out, then after get one basis enter it and show how much accumulated was taken on your half. Confusing I agree, but take your time.
