Couldn't they buy a copy of XWD and update the site as they wanted?

If they use the Registry utility Available to us, it would make a backup copy every time they saved and prevent them from losing anything.

They could also email a copy to you or anyone else if they were worried about losing it.

It sounds easy to me to have them spend $50 and make all the changes they want.

Otherwise, they could only update the specific pages individually. Name them properly and upload each one at a time.