Governor Lincoln Chafee says he and the General Assembly have most of the authority to approve a settlement in a legal challenge to last year’s landmark pension overhaul. Court-ordered mediation is set to begin next month. State treasurer Gina Raimondo was the architect of the pension overhaul passed last year by the General Assembly and signed into law by the governor. Raimondo and Chafee are both defendants in the legal challenge filed by five public-sector unions against the overhaul. Chafee says approval by Raimondo isn’t necessarily part of a settlement in the case.