It might be difficult to recreate this outstanding painting in one render. If you can, you're a better artist than I. I'd suggest doing the servicepersons as a second render from the Wall's visitor, then combining them in Photoshop, where you'll have full control over the opacity (reflection.) The challenge then will be to get the angles right, but with some effort, you'll succeed. Very good luck to you, and please share the results with us when you're done!