C check R3... throw to 1B who is next to base... if BR make a move to 2B tag her... if R3 takes off make a play on her.... practice this..
This wouldn't really work, the BR will run and stop at first, as soon as the 1B throws it back to the pitcher, the 2B will take off.
Teams usually just stop the BR at first, then have her steal on next pitch. Almost impossible to have a 1st and 3rd situation with less than two outs, unless your best contact hitter is up next, the BR will make the turn, or steal on the next pitch.