Of course, that's the very purpose of the assembly feature. DV scans all its three TM levels (TM, terminology and lexicon), and assembles a translation prioritising terms that come from lexicon, then terminology database and finally the TM. This means that if your client has provided a glossary you are supposed to adhere to, you can import it into the lexicon and it will take way against all other terms you may have stored in other connected databases.