Since they have been forgotten, it means that those ancestral graves have been a long time ago. Without inscriptions, it is naturally difficult to verify. Yes, according to Feng Shui in southern China, we can deduce the general context. For example, "north-south". In other words, the oldest ancestral tomb should be in the south of the new tomb, and the tomb mountain stretches from south to north. There are also "eight places on the ancestral home", which means that the new grave (the grave of the descendants) can only be located below the grave. For example, in a "vessel", the two openings at the top are the upper part; the two openings at the bottom are the lower part.
As for the north, due to geographical differences, I wonder if the "feng shui" theory that has been passed down for hundreds of years is different from the south? I don't know this either.