If you open the document and press Alt-F9, you will see the DATABASE field codes, the first of which looks like:
Code:
{DATABASE \d "{FILENAME \p}/../Dummy.xlsm" \s "SELECT `Flat/Door Number`, [Address First Line]&' '&[Address Second Line] &' '&[District]&', '&[City]&' '&[Postcode] As `Address, Locality & Postcode`, `URC`, `Ref Code`, `Eligibility` FROM [Data$] WHERE [Eligibility] = 'Registered' " \b 58 \l 9 \h }
Simply replace 'Dummy.xlsm' with the correct file name and save the Word document to the same folder as that file.