Your application is about automatically transferring row(s) of information immediately upon the selection from a primary drop down list. The page you're referring to on my site is about have secondary drop downs with secondary options based off of the initial selection. It doesn't automatically transfer choices. So, I'd say it's not the same thing.
But you ask if it's usable? Of course, depends on what you change about the way your sheet is to be operated by users.
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Yes, I was indicating you should put child part numbers in column A, and that those child part numbers be "unique". Those cells would be copied as well with the updated version from post #24, but I see I forgot to keep that update when i added something in post #26. My bad.
Here is the correct version that includes all:
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