Try Cv(S) against Kn(F) since, as Lawrence has noted, these are often alternatives for the same troops and are found in a lot of Book 3 armies, so often come up against each other.
If the Cv(S) go in and win the first combat, the next Kn(F) is overlapped, so is likely to lose, then gets -1 for F while the S gets +2 at the same time. However, if the Kn(F) get first hit, everything changes.