I'm trying to create a pipeline from a clients data. We receive daily data dumps and I identify which loans should be in our pipeline by looking up names from a roster to by loan. I then assign an ID to that loan using addindexcolumn function. The problem I'm having is how do I add to this base data set with new loans coming in daily and keeping the already assigned ID's static to the base data set, but then adding new loans and assigning ID's to them. Since there are dupes, I created a file time stamp and then created a key with the loan ID and time stamp from each data file. Should I create a base data set, and then append the new data file? Or have powerquery create a new file with every additional data file, load all the files from the file folder? I'm confused on my approach. Thanks!