Well, it has become kind of a habit to use third party software. PowerISO is good. Heard windows needs a rstart when you mount, unmount and then mount the same iso and want to have the same virtual drive.
As I suggested some time ago to you, Virtual CD maybe is the way to. You just need to add the ISO('s) to your list of available images, create some virtual drive('s) (if you're unhappy with the system created one), use all time the same virtual drive for some specific ISO and that's it! I have it now running in Windows 10 TP and it just works as it should! The version I've installed is 10.1.0.13 not thelatest on, by the way! An other similar is Farstone Virtual Drive 16, unfortunately also Payware!
Had no time yet to test Virtual-CD, but I will try it later on or maybe tomorrow. The Farstone one seems to be ok as well and has a good price too. Thanks for the tip !