How to create Word 365 protected fields?

Please refer to the attached Word 365 document, Family Info.docm, which when opened looks like this:

As you can see, there are three fields defined, and if you turn on protection, you can edit only those fields:

I would like to add protected fields for Name and DOB. I turned on field codes, and saw:

... so I added FORMTEXT fields for Name and DOB as well:

... but when I turned off field codes, I still only saw the three fields (as in the first image above), and when I turned on protection, I was still only able to enter the original 3 fields.
Please note that the doc does not use "form fields" (from the Developer tab).
Any assistance would be greatly appreciated.