Filter which rows to merge

From the Google Docs Add-on

Click the Select Spreadsheet button to chose a file to merge data from. In the example below, the Label Merge Customers file was chosen.
Then select the sheet in your file which contains the data you need to merge.
Click the Create Row Filter Column link as shown below:

Now open the Google Sheet selected above and scroll to the last column. You will find a new column called Filter Rows to Merge.
Then type 'x' (or any other text ) for the rows you wish to exclude from merging. As shown in the image below, you can even create a formula to determine which rows should be excluded. In the example below it is excluding rows for customers who's gender is equal to "F".

When labels are being merged, the add-on will automatically enter the date and time of the merge in the Filter Rows to Merge column.
If you wish to re-merge the rows you need to clear the content of this column.
If you delete or rename this special column the filtering will be ignored and all rows will be merged.