The whole idea with flash, especially flash in the studio it to fully control the light in the space.
That’s why most of my shots in the studio are taken at f/8 and 1/200 of a second at ISO64. This gets rid of any ambient light, just allowing the flash to light the scene.
But just occasionally you want to introduce another light source, here we have candle light and flash carefully balanced. Wide open, lowest ISO and I kept dropping the shutter speed till the candle looked right then lit the rest of the scene with flash. Tricky but easier when you tether to the computer.