This request is for the merge to first look to the Master record, but when its empty to default the selection to another record that has data. (the entire reason we are merging right?) we want the data from one and the data from the other. See image for an example. State and Postal Code has no data on the master record, but those radio buttons are ticked, when the 3rd record does have data for those and you would have to manually go down every piece of data and select it.