tie in in WordNet English dictionary

1. 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"
   associate  tie in  relate  link  colligate  link up  connect 
   
2. be in connection with something relevant
   "This ties in closely with his earlier remarks"
   tie in 
   

tie in in English Wiktionary