Thinking about adding a switched overhead light in dining room

Hi all, In our dining room (formerly a living room before the previous owners built an addition in the 90s), there is a light switch with three switches as you enter the house from the outside. I was wondering how much trouble it would be to add a 4th switch and put a ceiling box in for a semi-flush overhead light connected to that...? I'm guessing it would depend on where the stud is that the existing switch box is attached to (ie, is there room to add a new box to the left of the switches, which are ver close to the door frame, on the right side)? Would I need to pull out the existing switches, remove the existing box and put in a 4 gang box? Or is there an 'add-on' box out there that would look seamless with a faceplate over it?