tie-in

(noun) a fastener that serves to join or connect. Synonyms: link, linkup, tie. Example: "The walls are held together with metal links placed in the wet mortar during construction."

(verb) be in connection with something relevant. Synonyms: tie in. Example: "This ties in closely with his earlier remarks."

(verb) make a logical or causal connection. Synonyms: associate, tie in, relate, link, colligate, link up, connect. Examples: "I cannot connect these two pieces of evidence in my mind." "Colligate these facts." "I cannot relate these events at all."