The biggest thing is to - practise just walking through the spooky end thinking about this: sitting a little more on the inside seat bone, using the inside leg and both reins (appropriate length) in a conversation of aids - so maybe the inside leg should just lay at the girth or maybe it should push/soft/push/soft with each stride, while keeping the rein connection elastic. I have always found that the inside leg and outside rein connection is most suitable in these situations, without changing the bend. But the strategic use of inside leg and sometimes slightly compromising on the line of travel is best - so maintaining as much relaxation as possible, maybe not getting right into the corner for now, but keeping the rhythm and getting back to relaxation is important to build the trust. (here is what I see most often with riders: horse starts to drop the inside shoulder, lifting the neck and changing the bend - rider grabs inside rein and pulling on the outside rein, which creates profound incorrect bend and horse gets away with ducking out of scarey corner.) Keeping alignment in the horse’s body and neck shoulder area, keeping the forward with well balanced rider is what is needed. Rider needs to keep active, giving/taking/giving aids.