I think for leaning into each other if you do lots of transitions. Walk- trot - halt - trot etc. Mix it up. And I mean lots of transitions. Say every 4 to 5 strides. This should keep the horses so busy they should have a hard time leaning into each other. Also changes of directions and turns. They won't have time to lean and when they quit leaning even if just for a stride or 2 reward by just going straight and same gait for a while. THen if they lean start all over again. If it is just one horse leaning say the right horse. Drive a circle to the left and use the whip to get the left horse to bend and push the right horse upright and over and keep the circle big. This can be hard for the left horse because you are asking them to bend and hold the outside horse up but it can help keep the other one from leaning. Often times on a turn if your inside horse isn't bending properly the outside horse will end up leaning in on the turn anyways.:-) Lots of luck. Diane Kastama