Why must clients exist when radius starts?

Is there a configuration option that will allow me to put a client IP in the clients file without the client actually existing yet? It seems when radius starts, if a client doesn't exist the daemon dies. I looked in the archives but I don't quite know what to query for. Also is it the case that when the log is rolled, the daemon re-reads the config files and would die if it can't contact a client at this time? Regards Doug P