Replacing a field

I am trying to create a salutation (Dear First Name). Sometimes the first name field only has initials and the middle name is what should be used. In all cases the middle name field is empty unless there are initials.

Can you please help with a script.

If the middle name field only has content when the first name contains initials, then you should be able to just use the following:

return (Field("MIDDLE_NAME") == "") ? Field("FIRST_NAME") : FIELD("MIDDLE_NAME");