A99 request - Depth of Field Bracketing

I'd like a firmware upgrade for something I think would be called "Depth of Field Bracketing".

In other words I want 3 photos - one at the selected aperture, one (say) 2 stops larger, one 2 stops smaller. The camera could adjust the shutter speed &/or ISO to keep the exposure the same. Then I could choose which depth of field suits best after the event, without simply hoping the subject will remain still while I fiddle with settings manually.

I tried using Shutter priority and exposure bracketing, but the 2 stop over and under exposure is a serious negative aspect that a firmware update could solve neatly.