Hello Paul,

Any WebSite X5 site built using the Professional version must be opened in the Professional version.

There is a completely free version available:

http://www.websitex5.com/en/website-builders-comparison-chart.html

Whilst limited in features and functionality nonetheless it may suffice if your wife's requirements were not stringent.

No matter which version you choose, do ensure that your wife's project is not opened in your Professional edition...  as this would convert the project and render it incapable of being opened in the lesser editions...  you would end up with even more work  

As an alternative you could build the site in Professional and make liberal use of the Dynamic Content Object, allowing your wife to make regular edits and updates without even opening WebSite X5 at all:

http://help.websitex5.com/en/v11/evo/index.html?ogg_dinamico_ht.htm

Kind regards,

Paul