[Plugin: Custom Contact Forms] Using fixedEmail with custom forms

Hi — this plugin has me 3/4 of the way on a simple yet crazy-hard fix. I have my own, very tight form. I have it working with the custom HTML form script, thank you page working, email arriving.

However, I would like to use the validation available with fixedEmail when you use the plugin constructed forms. I would also like to set three of the four fields as required. Is there a way to use those functions in my own form code?

https://www.ads-software.com/extend/plugins/custom-contact-forms/