The real power player in this whole scenario is the electric utility. Your first step should be an on-site, face to face meeting with your utility’s service planner. The utility has the right to deny power to either property owner if they don’t conform to practices that your State’s Public Service Commission has authorized the electrical utility to use. While this may not allow feeders to be run through another persons building, it would certainly allow other options you may not have preferred to keep costs down. Even as electrical inspectors, we still have to bow to the electrical utilities while they have State approved jurisdiction and this is defiantly the case here. I hope this helps.