I had my hotspot programmed for both TGIF and BM and it was working beautifully through the DMR Gateway.

Through the DMR Gateway.  There's the clue.

TGIF recently made some changes and made the popular TGIF TG31665 "secure".  In order to get on the secure TG I was required to change my Pi-Star/Configuration/Expert MMDVM Host settings

And there's the problem.  You were using the Gateway, so the change(s) you need to make should be made in the Pi-Star/Configuration/Expert/DMR GW settings, not in the MMDVM area.  You basically told MMDVMHOST to stop talking to/using the Gateway and start talking just to TGIF.

With the NEW TGIF changes, is there a way to keep my original dual network programming while being able to log into the secure TG31665 so that I may enjoy the TGIF 31665  again??

Yes, and very easily in fact.  Go into the Pi-Star/Configuration/Expert/DMR GW settings, look for the Password=passw0rd line under the stanza for the TGIF network, and change passw0rd to the secure password you were given.  Apply changes.  Done.

73,
Joe, WB3IHY