In AddAdminBC.java, it seems like the "import static" is causing it to break Overlord's AddAdmin command. I don't know much about java and why multiple files using "import static" for the same thing would be an issue, but it seems to work fine with a few changes:
line 18
import org.lazywizard.console.CommandUtils;
line 53
if (!CommandUtils.isInteger(tmp[0]))
line 61
final FactionAPI faction = CommandUtils.findBestFactionMatch(tmp[1]);
After these changes, you would still need to change the syntax in commands.csv from "addadmin" to something else like "addadminbc", or Overlord's addadmin command seems to overwrite it.