There is a new feature when working in the Merge to HDR Pro feature in Photoshop CC. If you set the Mode to 32 bit, under the histogram is an option to “Complete Toning in Adobe Camera Raw”.
Enabling this option, changes the “OK” button to “Tone in ACR”. Clicking “Tone in ACR” tells Photoshop to convert the 32 bit HDR layer into a Smart Object and automatically apply Camera Raw as a Smart Filter.
Then, simply apply your desired settings in the Camera Raw Filter and click OK. Because you are working with a smart object, not only can you double click the layer thumbnail to re-edit the Camera Raw options, but you can also use the Smart Filter mask to selectively show and hide the effect AND change the Blend Mode and Opacity of the filter!
Note: only the following Blend Modes are available when using Camera Raw as a Smart Filter: Normal, Dissolve, Darken, Multiply, Darker Color, Lighten, Linear Dodge (add), Lighter Color, Difference, Subtract, Divide, Hue, Saturation Color and Luminosity.