If you want to simply copy everything in company A for a file and replace what is in company B simply copy the file to the other company folder, delete or rename the one that is there and change the extension of the one you copied in.  If you want to keep what is in company B but append the data from Company A to it, copy the file from the company A folder to the company B folder, then load the Pervasive Maintenance utility, choose Data - Copy and select the Company A file and copy it to the company B file.  This is a blind copy, it doesn't check to see if the entry already exists so you can end up with duplicate records or, if the data structure of the file in question does not allow duplicate keys, you will get a Status 5 error during the copy.