Yes, you can update the file in your Dreamweaver users configuration folder: /Configuration/Shared/WebAssist/FormValidations/Scripts/WAVT_Scripts_PHP.php
If you update the file there it will use that file when applying on new sites.
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These out-of-the-box solutions provide you proven, tested applications that can be up and running now. Build a store, a gallery, or a web-based email solution.