Can I add a Boot Camp partition as a secondary drive in Parallels?

This is all getting complicated for sure! There is a way that you can set up your Boot Camp partition as a secondary IDE drive in Parallels, and I'm suspecting that's exactly what you seek. Let me step you through the surprisingly easy steps...

First off, you want to start up Parallels and then use the Windows "turn off computer" feature to ensure that your virtual machine is not running. You can't just pause as changing the configuration while your VM's paused can really mess things up. Stopped? Good.

Now you'll want to go to Edit --> Virtual Machine... and you'll see this:

Click on "Add.." on the lower left:

You want to add a Hard Disk, so make sure that's highlighted and click on "Next" to see your options:

Choose "Use Boot Camp", click "Finish" on the bottom and you're done. Your configuration should show the new drive too:

Now the first time you restart your virtual machine, you'll see it tell you that new hardware has been detected, an "IDE drive", and that, after a little bit of behind-the-scenes tweaking, it's ready to use. At that point you can simply go to "My Computer" and you'll see the new drive appear, like magic:

That's all there is to it.