Basis isn't input from anywhere except by the Preparer. 1099S only has the sales price.

If the property was sold very shortly after the death, then the stepped up basis is probably good enough. Deducting the selling expenses can result in a loss.

If there were improvements made before the death, then the stepped-up basis includes them.

If there were improvements made AFTER the death, but obviously before the sale, then the stepped-up basis(FMV at death) PLUS improvements goes into the basis, since the FMV was made at DOD. But then you need a DOD appraisal before the improvements were made.