@createtaiwan Considering that the ground seems to be uneven anyway I would tend to raising the ground and trying to match the artwork when aligning the fence. But I haven’t tried it yet how this would look in the landscape context. We should ask @theluthier for a final word since he’s the landscape modeler.
Putting the original fence parts into one collection and the linked duplicates into another and then linking the collection with the linked duplicates into another file would work. By this you keep the overview on how many different parts are in your fence.