With the parallel suspension's inherent design flaws, I have to think bump steer is a bigger problem than the hair splitting geometry we are discussing at this point.
Alignment geometry is making sure the wheels are pointed the right direction to track straight on a level road.
Bump steer is a whole other discussion. It is actually roll steer engineered into the suspension to try to straighten the vehicle as it rolls in a turn. It is less scary for the average driver to go straight off a turn and hit something than to go backwards off the road and whack something they can not see.
For front suspension the rack or tierod height is moved to make the wheels turn a bit as the body rolls.
For rear suspension it depends on the suspension used, whether parrallel leaf springs or some form of multilink. On parrallel leaf springs for example, the front mount is lower than the rear mount on the shakle. As the body rolls this causes the live axle to turn a bit to straighten the vehicle. This can be reduced by moving the front mount point up a bit bit cate must be taken to not move it higher than the rear. This reduces the amount the axle turns. Of course the pinion angle is changed doing this and must then be corrected. Two link like the 60's Chev trucks, 3 and 4 link all require different procedures.
