Combine

The Combine action will make sure files exist in both folders, without renames or deletes. New and updated files are copied both ways. Nothing happens to renamed and deleted files.

You have multiple PCs in your house. You add pictures, tunes and/or documents to both computers. You do not delete or rename files often and when you do, you do not want those deletes or renames recreated on the other computer. In essence, you want SyncToy to insure that all files in these folders exist on both folders at the end of a Run. (Combine is the same as Synchronize but without the renames and deletes.

Combine is the SyncToy action to use.

Any file that exists in the left folder but does not exist in the right folder is copied from left to right.
Any file that exists in the right folder but does not exist in the left folder is copied from right to left.
If a file has changed in either folder, the newer file is copied to the other folder, and the older file is renamed but not copied.
No files are deleted.
When the run is finished, every file that existed in either folder will exist in both folders.
Note: SyncToy does not delete folders.