I guess I want to make sure I'm thinking clearly because I've never done this before. I have a single server with 2012 R2 Std running as the PDC with all FMSO roles. I'd like to add a 2008 R2 Std server as a secondary controller. The domain and forest functional level are both Windows Server 2008 R2. It won't be a problem to add that second server as a domain controller, will it?