Well, not entirely replacements. Maybe just additional is more accurate. I have several branches where subsequent descendants have decided to place a more durable granite stone to sometimes replace, but more often supplement the original stone.
An example is Hubby's Walsworth branch, located in Clark Cemetery. The stone below shows the original obelisk style stone, along with the newer granite stone behind it.
While the face of the stone, with the family name on the base is not the patriarch, he is the son of the original Muskegon county immigrant. Artemas and his wife Amanda are on what I would call the front of the stone. This side faces the U-shaped drive through the cemetery. On one of the other sides can be found that patriarch Elijah and his wife Lucina.
The gray granite stone, shown below, has the family name and all the names from the stone. Unfortunately they are kind of jumbled around. Elijah and Lucina's names are on either side of the family name, in the corners. Artemas and Amanda are on the bottom, left side, and the two other names together on the right side.
These other two people, James and Frank are on the third side of the original stone. While they have the same surname, they don't fit any of my husband's known family members. I am only guessing, but perhaps they are cousins of some degree.
For the supposed age of these stones, the letters are fairly clear, and unworn. But I am glad that both the original and the new one are together.
When it comes to cemetery stones, my thoughts are, the more the merrier.