After going over the issue with several other experienced developers, I am experimenting with cookies here. No - not the type you eat but the type that your browser uses.
I'm hoping that whatever login issues we've had are a thing of the past and that now there will be no problems going forward. If you do experience issues and anomalies, just let me know. I'm relieved that, if it works, I can turn to something more productive than this effort scouring has proven. If it's working, then no news is good news! 

