The Synod questioned Da'an's capability but removed Zo'or from the position when it became clear that Da'an could not have known about the Doors conspiracy ( Resurrection ). Zo'or was later appointed the Taelon Ambassador to the United Nations, a role previously filled by Da'an. This was ostensibly because the Synod wanted Da'an to focus on his duties as the North American Companion.
adjunctive (plural adjunctives) a connector joining two components of the same weight, such as a coordinating conjunction (manufacturing) a substance added as a supplement; often in the phrase additives and adjunctives.
Enhancer or Enhancement. From the word enhance: to make greater, as in value, beauty, or effectiveness; augment; to provide with improved, advanced, or sophisticated features. This would satisfy the request for a word that applies to something that adds value to something else. But I don't think I've heard it used to apply to a person who adds to the value of something. I believe that the words adjunct and adjunctive could be used to express the concept of someone or something that adds value to someone or something else.