How to import User-defined fields from an Outlook Contacts form into a new Contacts folder?

Question

I have a custom Contacts form that I use with a number of user-defined fields that I created when I created the custom form. I use this form as my default Contact form in my default Contacts folder. I have created another folder for a separate group of contacts, and made that same form the default form for the second Contacts folder. Whenever I open a Contact in the second folder (Business Development), everything works fine. My issue is when I try to create an email mail merge which includes some of the custom fields, like "Salutation". The email mail merge document can't find the fields and the data within them because the fields themselves, although they are in the form, and the form is published to the second folder, are not listed in the "User-defined fields in folder".

So my question is how do I import these custom fields contained in the form, into the User-defined fields in the folder so that I can use them with mail-merge?

Thanks in advance for your help and guidance.