Won’t taking it in at the waist by 4 inches make the rest of the corset look strange?
No. Look at it this way. Let’s say you have 4 seams where you can take it in. That really makes 8 since there are 2 halves of a corset. Divide 4 inches by 8 for a result of ½ inch. You take in a seam ¼” for a total reduction of ½”. This means you are only taking in each seam by ¼ inch at the waist. That is easily done without changing the silhouette very much.