>>8828859
PcNerd has a mod on Loverslab called Flat Chested Sims which has a convenient overlay with degrees of intensity that gets rid of shading below the breast shape. It's what I use for pretty much every sim with smaller breasts, since the default shading intensity is just too much.
I believe it should work with just about any breast mesh since that sort of thing will just be a texture detail, although you might need a nipple overlay since I noticed it does have a tendency to cause texture misalignment with some meshes.