I'm not an expert so this might not be the best advice. Since people have said that most likely your party of 3 will be sitting at a table for 4 you could try canceling your ADR and immediately searching for 4 and see if the one you just canceled comes up. If not you could then search again and try and snag your original ADR for 3. You might be better off trying this with one of your less popular ADRs and maybe in the middle of the night when most people are sleeping. I don't know if this will work so if you try it and it doesn't please don't come after me