How can I make a Microsoft Word fillable form so that additional pages can be inserted by the user filling out the form?

You have two good answers already.

Here are a couple of resource pages that can give you more background.

• Create a Form Using Word Content Controls by Greg Maxey
• Create forms that users complete or print in Word - Office Support

Do not mix legacy Form Fields and Content Controls.

The actual steps depend on how you have created the fillable form, but the general principle is that if the end of the Word document is editable, the user will be able to add to it.

If your document is protected for forms, include a section at the end that is not protected. If your document uses protected area exceptions (editable areas are highlighted in light yellow), ensure that the last paragraph mark of the document is editable.

If you are using content controls for the data entry places in the document, do not use the Restrict Editing pane to protect the document. Instead, insert an empty paragraph mark at the end of the document; then select everything except that last paragraph mark and click Group > Group in the Developer ribbon:

That inserts an invisible Group content control around the selected text, which prevents editing of anything that's outside the entry controls but still inside the Group control. Users will be able to add or edit anything at the final paragraph mark, including page breaks, section breaks, text, pictures, etc.

If you're determined to stay with legacy form fields, the equivalent is to insert a section break (either Continuous or Next Page) at the end of the form. Set the editing restriction to "Filling in forms". Only when the document contains two or more sections, the "Select sections..." link appears. Click the link and, in the dialog box that opens, clear the checkbox for the final section.

The main drawback of legacy forms protection is that it disables many of Word's useful features, even in the unprotected section(s). For example, you won't be able to insert text boxes or bookmarks or run a spell check as long as the restriction is turned on.

Thank you very much

Thank you very much