Sheila set up a single bounce beam off ITMY, and ran the AS centering loops. We could see beam on AS_C. I ran a quick test by moving the BBSS in pitch and yaw using the sliders. AS_C shows clearly for 6 urad of pitch motion, the only movement on the diode is pitch. 3 urad of yaw motion also only moves in yaw. The oplev shows pitch and yaw movement during both times, which indicates the oplev is a fairly cross coupled sensor.

Based on this test, I don't think we need to do any other work to un-couple the BBSS pit and yaw dofs.