Scott,
You are correct, -- they do not resize. When I changed the center opening to 36" the left opening remained the same asit was and the right side reduced accordingly. it modified the frame but did not change the cabinets behind the frame. When I went back to the frame editor after going to main I highlighted all openings and asked them to equalize. the image simply froze and did nothing.
When I initially did this, I simply modified the frame, added doors and drawers, then changed the width of the cabinet. I did not wish to change one cabinet only so it resized everything as a unit equalizing all openings automatically.------
I just created a face frame on a single cabinet and it behaved the same way. I could change the width of the center opening with the drawer rail in place which left me with three openings all of different widths, but I could not get it to equalize after the change was made unless I removed the drawer rails from all openings. So here it is -- I ran my fingers before engaging the brain once again

. Using your initial construction method will allow you to resize the individual openings and return them to their original configuration - if you have a need to do so.You can still resize the opening width by simply entering the width of the opening in the opening width dialogue box of the faceframe editor even with the drawer rails in place whatever construction method you choose. It is the equalize feature that can fail to perform as we might like.
I can't help but think this might be a bug for the programmers to look at. I think if you can change an opening which has a drawer rail then equalizing should be a simple push of the button without having to remove and replace drawer rails. Another observation is that if you change the left or right opening you can equalize the other two openings but you cannot equalize the two end openings if you change the middle opening. Would be nice to select and equalize whichever openings you choose, but honestly-- I havent built enough three door cabinets in my entire career to be worth the effor it might take to make such changes. As far as creating a face frame with three custom or equal openings, it takes far less time to just do it, by whatever construction preference, than it did to write any one of the posts i've submitted
