What are the other mountings and check the content of the cue files (it's just a text file)

Hi Dominus, here's the section from the config file: (I've started using D-FEND reloaded as a front end and config manager to help keep me right)

keyb US 437
mount C "C:\Users\Thom\D-FEND~1\VIRTUA~1\"
mount Y "C:\Users\Thom\D-FEND~1\"
imgmount D "Y:\CD1" "Y:\CD2" "Y:\CD3" -t cdrom
mount -u Y
mount E "E:\" -t cdrom -IOCTL

Instead of running straight off the CD's, I used D-Fend to create a CD image of each disc and the game now runs off this image of CD1, but at the point in the game where it requests CD2 it doesn't switch when I press CTRL F4
When I created the CD images, it seemed to save them as a generic file type instead of a .CUE/ISO etc possibly because the CD's contain a mix of different file types? Surely this can't be the problem though, or it wouldn't run at all?
I've searched for an existing D-FEND profile for the game, but of course there is one for every other game in series except Privateer 2! If I can get it working, I will, of course, upload it for the good of the world 😀
I feel like I must be missing something obvious...

Privateer 2: the Darkening cds are w/o cd-audio so - use .iso.
Imho, the easiest way is - install virtual cd/dvd (I use A52% FE). Mount the image in this virtual drive then mount this drive as d in DOSBox. When you need to change the cd - just mount the 2nd/3rd cd-image and switch back to DOSBox.
The switching is the trouble if the game isn't supporting ALT+TAB. But AFAIK this is actual for several glide games only.