I wrote Marriott Concierge. Here's the first response:

"Dear Travelismylife,

I appreciate the opportunity to assist you with your Marriott Rewards
account, and I apologize for the delay in responding.

I sincerely apologize for the misinformation and inconvenience you
experienced at the ************* Marriott. I have confirmed that the
Global Rate Break Promotion cannot be combined with any other offers,
including the Buy One, Get One Free Elite Exclusive Offers (EEOs). "

Response two from yesterday:

"Dear Travelismylife,

Thank you for your reply.

I have researched this issue further, and the Buy One, Get One Free Elite Exclusive Offers can, in fact, be combined with the Global Rate Break Rate. I apologize for the incorrect information I provided in my original response and the confusion."

I am waiting to hear about using the Hertz promo and EEO.