In Account Settings > Firm Defaults > Custom Fields, you will either want to create a new field or edit an existing one. If you select a Dropdown, Radio, or Checkbox field type, then you will see a checkbox to Save Option Names as New Merge Tags.

If this box is checked, each option you've created below will be saved as a merge tag. Only the option selected in the case will appear in the document.

In the example below, we have created a dropdown field for What is the paralegal's name? and have added 2 paralegal options for Mandy and Kelly:

In Account Settings > Firm Defaults > Doc Creator Templates, we have added the name subtags into our document by clicking the + button in the left hand column and then dragging and dropping the tags into the template.

To select the option we need for a specific case, we will do that within the case in Additional Documents > Doc Form Fields > +Add Form Fields by selecting the template we need.

After we select the template, all available fields for that template will appear. We will then select the paralegal name that we need.

In Additional Documents > Doc Creator, we will select the template and click +Create Document.

Once the document is generated, we will see that the paralegal option we selected in the case has populated within the document: