Forms using content controls do not need to be protected for forms. If you want to protect the areas that are not fields, then mark the fields with 'Editors' and protect as read only. You may find Insert Content Control Add-In useful in making the changes.

You can validate fields using macros, but this requires the use of macros and you cannot force the use of macros.
Frankly the best approach for such a form is to create a PDF form, but for this you will require software, such as Acrobat, capable of creating such a form.

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Graham Mayor - MS MVP (Word) (2002-2019)
Visit my web site for more programming tips and ready made processes www.gmayor.com