P: (Masking) Like to reuse my LR masks in intersection or subtract

It would be really nice if I had the option to "Add" or "Subtract" from one mask, by selecting another. A good example of why is when I select a new mask and select "subject" for example. But it doesn't select all of the actual subject, and/or selects things that aren't the subject. I then have to go through and either Add or Subject by selecting Objects, or Brush, or whatever else. Then, if I want to select the opposite, I have to do the same process, just opposite buttons. 

I know there is the "Duplicate and Invert" option, which is great, but that only works if you're starting a new mask, not if you've synced settings from another image. For me, I'll edit a photo in a set, get it how I want it to look, apply the settings to all images, then go through making adjustements to each photo to give them a uniform look. I don't do presets, but this is close enough. 

Having an option to click "Subtract" and selecting "Mask 3" having it remove everything that is selected in Mask 3, for example, would make for a much faster workflow. 

Yes. This can reduce time to procesd

Yes, needed

This option will be very useful