When you tried parenting,have you tried this: you've loaded the FireCore, fine. Load the Fire, now, click on the drop down menu and make sure the Fire is selected. I like to use Ctl+i to open the proprties window and set the parent. Normally the parent would go to the body. Now select the FireCore prop. Click on the dropdown menu and see if there is a body part. If so, select and now you should be able to move the whole prop.

I must remember to remember what it was I had to remember.