This pattern is common if your new file contains a superset of all the data. It could be a transactional file that grows in length each time or it could be a dimension/lookup table (such as Customers) that can change slowly over time, and you always want to see the latest version. My advice to all my Power Query students is “zero touch the file”. In other words, your objective should always be to have the absolute minimum amount of interaction with the source files possible and push all the work into Power Query. This will minimise the amount of work/rework you have to do in the future. Thinking about the use case here “load the latest version of a file”, the question becomes “how can I make this zero touch”? There are a few issues to consider including naming/renaming of the file and also archiving old copies of the file. This doesn’t sound like zero touch to me.
Read the whole thing and check out the video.