Add manual static custom tags that are hidden

I have dozens of website feeding to a single google sheet. Each of these websites have two forms. One form is called “SEO” and the other form is called “SEM.” I would like for this name to automatically be added into its own column in google sheets along with all the other fields from the submitted form.

I would like to also add a second custom static tag manually that describes the website. For example for a cusotmer in Florida that has three websites, I want a tag for the contact form on his Orlando site to append “ORL” as a hidden field with every form submission. For Jacksonville it would be “JAX” etc.

This way every entry into Google sheets would have one column that says either “SEM” or “SEO” and the other column would say either “JAX” ORL” or “DAY” along with their name, email, phone, etc.

Adding a simple manual hidden tag sounds like something a lot of people would want, but I can find absolutely nothing online about this. I have been hitting my head against the wall on this.

Any help would be greatly appreciated!