Have your SS cheat a little by shift her a few feet closer to third base buying her a little more time to stay in position. The more important thing is try and give the 3rd base coach a different look on each pitch when there’s a runner at second. Try and set up a communication system with your third baseman and SS as to who will cover 3rd on each pitch. If the two took undetermined turns at covering third, it’s harder for the 3rd base coach to call a play and know for certain the defensive coverage. Your pitcher should also be in the know so she can cover the third base side of the field on bunt.
If you have a strong pitcher who has good control and can waste a pitch, call for a pitch-out when you suspect the steal is on. This will allow your SS to break early knowing the pitch won’t be hit. Even if you guess wrong, it gives the 3rd base coach something to think about.