'tie in' definitions:

Definition of 'tie in'

From: WordNet
verb
Be in connection with something relevant; "This ties in closely with his earlier remarks"
verb
Make a logical or causal connection; "I cannot connect these two pieces of evidence in my mind"; "colligate these facts"; "I cannot relate these events at all" [syn: associate, tie in, relate, link, colligate, link up, connect] [ant: decouple, dissociate]

Synonyms of 'tie in'

From: Moby Thesaurus