Question

Is there an option in the scanning settings to allow adding more pages to the same batch before completing the scanning process in FlexiCapture 12, so the Scanning Station waits for the user to confirm that all pages are scanned?

Answer

All the available related settings are present in Scanning Station>Tools>Options>Batch Options:
 

By default the "Each time when scanning is initiated" setting is selected.
If the number of scanned pages is always the same, the "Every N pages" option should be used.
Alternatively, it is recommended to use the "Never" option but each time it will require to create a new batch manually.