It has always been possible to add formulas (or functions) in the Excel templates, that you are using in InterExcel400, but with the latest version of InterExcel400 it is now possible to add dynamic formulas – added via the InterExcel400 conversion definitions (inside the layout).

With this feature you can e.g. do this:
a) If a cell is empty you can make it refer to the cell just above.
b) Insert almost any excel function and you can even include spooled file data inside for function.
c) Add a SUM function to sum up all the detail lines.

These features are included in version 001173, which is available for download here:
http://download.interform400.com/shares/SW/InterExcel400.zip
(An updated manual is included).