Falloutnv how do i get the brotherhood of steel to fight with me at hoover dam if hardin is the elder now?

i did the still in the dark quest, retrieved the Brotherhood discs from the Black Mountain, Nellis Air Force Base and REPCONN Headquarters, handed over the reports to Hardin, collected the scout reports from Camp Forlorn Hope, Nipton, and the NCR, i cant get the vent parts for lorenzo cause hardins the new elder. WHAT ELSE CAN I DO?