I have 2 spreadsheets. Source data spreadsheet and Exisiting data spreadsheet. I do a Vlookup in existing data spreadhseet to get values from source data spreadsheet. There may be new entries in Source data spreadhseet that do not exisit in Existing data spreadsheet. I want to get those entries into my existing data spreadsheet. How do I do that?

is the data held on one sheet, or multiple sheets within the source spreadsheet

the data is in one sheet in the source spreadsheet.
for eg source spreadsheet wuld have

name hours
ABC 10
DEF 15
OOO 30

Exisitng spreadhseet data
ABC so a vlookup woul dgive me 10 from the source
DEF and 15 from the source

now OOO name is not in exisiting spreadsheet which I want to
be added from the source spreadsheet everytime there are new entries.
thanks.