www.wysiwygwebbuilder.com

I know, there is a way to attach external files to a WWB project, which will be copied into the publish folder by publishing the project - but I can't remember how to do this ...

I know, there is a way to attach external files to a WWB project, which will be copied into the publish folder by publishing the project

If you are meaning javascript/jquery or css files then you can you the "File Publisher" object.
Or if you are wanting to import pages from another project then you can use "Import a page from another project"
See the following:
https://www.wysiwygwebbuilder.com/site_manager.html

Wow, lightning fast response time - big thank you

Using the Site Manager did it the job