The folder comparison window supports automatic merging of folders into a common ancestor folder in a similar manner to the file comparison window. The first and third folders will typically be independently modified copies of the common ancestor (middle) folder.
Please see Three-Way File Comparison and Merging for information about the general circumstance that might result in three distinct revisions of a set of files needing to
be combined.
Performing an automatic merge
The automatic merging operation will merge changes from the first and third folders back into the common ancestor folder. The operation can involve removal, copying, and merging of files.
To perform an automatic folder merge:
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Perform a folder comparison between three folders. Merge will assume that central folder is the common ancestor of the first and third folders.
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Make a backup copy of the common ancestor folder. Merge cannot undo changes that it makes to the contents of the common ancestor folder.
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Select the rows in the folder comparison results list that you want to include in the automatic merging operation. You can select all files in the list by pressing Ctrl+A. Folder selections are ignored.
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Click on the Merge to common ancestor
button in the ribbon or toolbar to review what will be done by the merging operation.
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Review the proposed operations in the Merge to Common Ancestor window and click on Start to begin the operation.
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Merge will perform the merging operation, reporting any errors or warnings as they are encountered.
Understanding the results of an automatic merge
When an automatic merging operation finishes, the folder comparison window will be updated to show what happened during the operation.
If you have enabled the option to Hide unchanged rows in the ribbon or toolbar Hide/reveal 
menu, files that are now unchanged as a result of the merging operation will disappear from view.
Files that were successfully operated upon will be marked as Resolved, and their names will appear dimmed.
A bookmark icon will appear in the left margin of the results list to indicate what happened to the common ancestor file. A comment is often attached to the bookmark. To see the comment, hover the mouse pointer over the bookmark or right-click on the bookmark and select Edit Comment... from the context menu.
A conflict bookmark is attached to files that either could not be merged due to merging conflicts or unexpected errors. In either case, the bookmark comment will describe the problem.
Files that could not be merged automatically due to merging conflicts should be merged manually using the file comparison window.
How automatic merges work
Merging rules
The following rules define what will happen to selected files during an automatic merging operation:
| First Folder | Second Folder | Third Folder | Action |
|---|---|---|---|
| File | Copy the file to the second folder. | ||
| File | Delete the file. | ||
| File | File | If the files are unchanged then remove the file in the second folder, otherwise mark it as a conflict. | |
| File | Copy the file from the first folder to the second folder. | ||
| File | File | Merge the files in the first and third folders into the second folder. * | |
| File | File | If the files are unchanged then remove the file in the second folder, otherwise mark it as a conflict. | |
| File | File | File | Merge the files in the first and third folders into the second folder. * |
* Files are only merged if they are considered to be text files.