On the VersaLink B/C405 the option to combine files is located here. I do not have access to a B215 but it may be the same on your device.
I hope this helps.
I would suggest looking at the user documentation starting on page 122 it talks about different ways you can scan. It also mentions what to do if scanning one page from the glass or multiple pages using the feeder.
If you are still having issues after trying these steps I suggest that you call into our support department for assistance @ 1-800-821-2797.
I am trying to scan multiple pages to ONE FILE instead of creating a file for each page. I have checked various settings but it still does this. Help please!