I guess my only option as you describe it is to admit my suggestion was fake and it won't work at all.
At the time I thought it would work, but you have explained that you did everything right and it doesn't work, so I must have been wrong because I would never imply that you might be.
My point is that a picture is worth a thousand words. I don't want you to explain it again... my point is that no matter how many times you explain it I won't fully understand until I can look at and debug the code directly, and probably nobody else will either... and this means that no matter how I try I might misinterprit it and give the wrong advice.
The webassist extensions save a lot of time and do simple things without need to tweak at all. However we can't be sure it will always do everything you need regardless of your database setup or user experience. I wish we could. You can definitely design things that our extensions won't do... but they will still save you time even if you are a guru.
I am not building the site you describe and testing it, so I can make mistakes. If you don't want me to make a suggestion without building out a sample then I probably won't have time to answer many questions.