NandoDave - your understanding is correct.

Definitely be careful if it appears that the AMB FWNC rate is available during the week. Some people are under the false impression that this rate would be bookable without having a Fri-Sun or Sat-Mon 2-nighther (in Middle East it is Thu-Sat & Fri - Sun) included and that is mostly not the case. There were exceptions during Covid, but these days I would be suspicious if I encounter a property that allows use of AMB FWNC say from Tue-Thu standalone. As you figured out, the rate is available in conjunction with said "weekend" 2-night stay for additional nights, but that is unnecessarily expensive as we discussed prior to your post.

These days, unfortunately, the AMB FWNC rate is often inflated even above the best flexible rate (wasn't like that in the old days), so just book the two nights minimum and then book your other nights before or after the weekend 2-nighter separately at whatever rate you like, points, advance purchase, corporate rate etc. Multiple reservations are not an issue for a property and you can always give them a heads up via email requesting assignment of the same room and listing down your 2,3, 4 reservation numbers.

I never had an issue with that at many different ICs, but I also don't play games with room categories meaning I don't book a Club Suite on the certificate and then a base level room for the extra night(s) and expect to stay in the same Club Suite. If I want that, I ask for a "paid upgrade" offer to bridge the rate gap and then take it from there. Rest is negotiation and depends on several aspects like total length of stay, difference in room categories, how full the hotel may be etc. I have always managed to come to a good solution for both parties with sensible requests though.