Yes, but I think Robert Lansing either 1. Didn't care for the character and/or 2. Had other commitments.
In Greg Cox's books The Eugenic Wars, Gary Seven and Roberta Lincoln are key players in the saga and have large impacts on both the rise and fall of Khan.
Major K
"He guards the sleep of his pauper master as if he were a Prince." George Graham Vest
"We are alone, absolutely alone on this chance planet: and, amid all the forms of life that surround us, not one, excepting the dog, has made an alliance with us." - Maurice Maeterlinck