The destination part in the LR Import section contains the folders from which you can choose where to import to. So far so good.
I expected the structure I see there to reflect the structure on HD and for the most part it does, but for at least one folder it does NOT. In the HD Folder "Lightroom Folders" I have a folder called "Birthdays", contains subfolders for each person, again containing subfolders per year. Unfortunately this folder structure is lost in the destination tree. I do see the "birthdays" folder, but then I only see subfolders named after years, as LR always does (why ? search me....)
So, is there a way to get the destination tree to match reality ?
You have most likely imported these photos from the problem folder using the COPY option (accidentally).
And so Lightroom thinks that the photos are now in the folder where you told Lightroom to COPY the photos into.
You need to find the photos in Lightroom by clicking on "All Photographs" and then searching for one of them by file name. Once you find the photo in Lightroom, right click on it and select "Go To Folder in Library" to see where Lightroom thinks the photo is.