When you open the merge worksheets dialog box, the active worksheet name is displayed beside Merge. The active worksheet is always one of the worksheets to be merged.
You can specify the columns to use to match observations. Minitab matches the values in these columns from each worksheet and puts the values in ascending order. The other columns are sorted according to the specified columns, so that each row of the merged worksheet contains information for the same group. You also can specify whether to include multiple observations, unmatched observations, and missing observations in the merged worksheet.
For more information, go to How to set up By Columns for Merge Worksheets: Match Values.
You can specify the columns to be included or excluded in the merged worksheet.