1) Connected 2) Forming an adjunct 3) Joining 
• (a.) Joining; having the quality of joining; forming an adjunct. • (n.) One who, or that which, is joined.
A secondary treatment in addition to the primary therapy.
supplemental or secondary (but not essential) to the primary agent. Sometimes used to describe medications used to enhance levodopa therapy.
Ad·junc'tive adjective [ Latin adjunctivus , from adjungere . See Adjunct .] Joining; having the quality of joining; forming an adjunct. 
[adj] - joining
adjective joining; forming an adjunct
forming an adjunct.