Add Gen5 to existing Gen4 cluster

Hi,

I have an existing GEN4 RPA cluster running code 3.5.1.   Customer bought two more Gen5 and wish to join the existing Gen4 cluster.   Based on the best practices, we are recommeded to add the Gen5 as site control RPA (RPA1 & RPA2).  I look through the procedure generator and I can only find the add RPA cluster wizard but there is no procedure on how to change the site control to Gen5.  The add clsuter wizard will add the Gen5 as RPA3 and RPA4.