Just a note regarding feature visibility... We're working on better docs on DIFFzilla. Multi-file diff is documented but not as completely as it should be.
Right now all of the docs about diffing can be found in two spots:
1. Use keyword "DIFFzilla" in the Help > Index. This will take you to the section about using diff.
2. Docs outlining each field/option/button on the diff dialogs can be found using keyword "DIFFzilla dialog box" in the Help > Index. This includes each tab on the DIFFzilla dialog itself, and the Multi-File Diff Output dialog docs are below.
Please send any ideas you have for these docs (such as index keywords for better visibility) to docs@slickedit.com. Right now, the index markers are kind of all over the place, so I will be taking care of cleaning those up also.