If you want to do this with a mail merge then I would create a separate source document for each company and have a single merge field containing a series of dates. The data source would just contain incrementing dates like
20/9/2021


21/9/2021
22/9/2021
23/9/2021
24/9/2021

The more labour intensive (to create) method would be to devise a macro which asks for start and finish dates and prints out the relevant pages without using a merge source at all.

__________________
Andrew Lockton
Chrysalis Design, Melbourne Australia