Hi aphaits, there isn't anything built in for that but you can get that effect by doing a boolean and then doing a fillet after.

re:
> Additional Question: Is there a 'symmetry' function that can automatically mirror changes on both mirrored sides?

There is a mirror command that can be used with history updates like Pilou writes above but it's not quite the same thing as a live symmetry type function. I would like to work on a deeper symmetry function in the future.

- Michael