Hey Todd.
Not sure how complicated you need this to be... I am assuming you are wanting to minimize any coding into the form itself and want it to be as dynamic as possible.
I am assuming you have a list of Customers that are coming in as a secondary data connection. Obviously if you had additional fields in this list that could flag whether they needed additional information or not or a group number or soimthing the form could respond to this.
Typically you would just have a section for additional information and then have it hidden by default and use conditional formatting to react to the selection and unhide or not.
You could have multiple styles and use a designation to have multiple configurations of the extra data.
Are you saving this data back to a database for further processing and reporting?