Replacing Old data with New

Hello,

I have two data flows, (1) Old historical data and (2) New/changed data.

Anytime a new sale happens or a change in an old sale, it will generate data into my Shared folder CSV file. The CSV file gets updated daily with new/changed transacations.

What I have done so far is created two data flows, (1) for Old historical data set and (2) for new and changed data set. I have turned off refreshes on my old dataflow and created a daily refresh for my new/changed dataflow. I have brought both of these dataflows into my data set and appended new query and enabled load on the others.

Each vendor has a unique vendor #, which is used anytime a transation takes place. Anytime there is a new or changed transaction it triggers a complete refresh of all old transactions and loads them into the new/changed file. For example if someone makes a change to a old transaction, it will re-load all the vendors transations into the new data. Essentially what I am trying to do is replace all the old transactions with new transactions but when I do remove duplicates in the query editor, it only leaves me with one transaction line for each vendor. 

Say for example a vendor has 3 transaction lines in the old data, and then the system generates 3 new transacation lines due to a change, how would I replace the old lines with the new?