I recommend that you and your brother keep ALL of the executive rights (the right to sign an Oil and Gas Lease), keep ALL the rights of ingress and egress, and convey to the Buyer a 12.5% undivided mineral interest in the 75 acres as a Non-Executive Mineral Interest (NEMI). That way, YOU and your brother get to negotiate the terms of the OGML for the entire 75-acre Mineral Estate, and your 87.5% pro rate bonus and royalty, BUT Buyer gets his 12.5% pro rata bonus once you sign the OGML, Buyer gets his royalty if the well produces, and Buyer gets Surface Damages if there is activity on the Surface Estate. Win-win in my view.