How to generate interactive pre-filled subforms in document merge
Overview
An interactive pre-filled subform table in document merge refers to a table section inside a merged document that:
- Pre-fills automatically using data from a connected source (CRM, spreadsheet, or form).
- Displays as a subform table, meaning it repeats rows for related records (like line items, dependents, team members, or assets).
- Remains interactive in the final document, allowing users (like clients, vendors, or staff) to review, edit, or add more entries directly within the document before signing or finalizing it.
Check out the
sample form here to try interacting with the fields and see how totals update in real time.
Steps
- Create a new Merge Template.
- Go to Automate pane and connect the template to a data source if you want to pre-fill some fields using the field values from the data source.
- To insert non-editable pre-filled data (read-only fields)
- Insert the required merge fields for pre-filled data (such as Name, ID, Department, Service Type, etc.) and ensure they are correctly mapped.
- Choose the appropriate field type (text, dropdown, checkbox, date, number, etc.) based on the data you want the user to input.
- These values are automatically populated during merge and remain non-editable in the final document.
- To insert interactive pre-filled fillable field
- Use this for fields that should be auto-populated but still editable by the recipient.
- Insert fillable fields and map them to merge fields so they are automatically pre-filled during merge and remain interactive in the merged fillable form.
- To insert pre-filled subform table (interactive subform)
Use this for repeating data groups, such as line items, dependents, or asset lists. Click
Fields >
Fillable Fields >
Subform Table.

- Choose how to create it:
- Option 1: Insert pre-filled subform table - Use this if you want the subform to display multiple records like a list of services from a data source and choose the fields that need to be pre-filled. The subform fields will automatically populate from the source’s related list.
Note: Please note that to use this, the data source shall not be a CSV file. - Option 2: Empty fillable subform table - Use this if you want form fillers to manually add entries by filling in the fields (e.g., additional overtime tasks).
- Choose Create Empty Subform Table.
- Define the columns (e.g., Task Name, Hours Worked, Overtime Rate). Users will be able to add or remove rows when filling out the form.
Additional Note
To make it truly interactive, add formulas and conditional logic to the subform table so calculations update dynamically and fields respond based on user input.
- Formula fields let you automate calculations directly within the document.
- Place the cursor where you want to add the formula field. (e.g., beside a “Total” label).
- Click Insert > Fields > Fillable Fields > Formula under Advanced fields. You can also choose formula from the visual cue on the left side of the table.
Use conditional formulas like SUMIF and SUMPRODUCT within the subform table.
Define the formula expression. You can reference fillable fields by their field names.
Example: Total Wage = (End Time - Start Time) * Hourly Rate
For a subform: Total OT Pay = SUM(Subform.OT_Hours * Subform.OT_Rate)
- When users enter data or modify a value in a fillable field, the formula updates automatically. Click here for more info on formula in Writer.