I don’t have a suggestion for the specific location of your tear, but since your title lured me in, and this might help others:
I have a pair of “equilibrium” (never was able to find the brand online ANYWHERE- these are at least 12 years old) breeches that I LOVE. They’re olive/tan and hold in my jiggle thighs and flatter my shape. I wore them so much (and for SO long) That the crotch wore a big hole. You couldn’t see it while I was standing or while I was riding, BUT obviously when there’s a hole in your crotch it makes riding a bit uncomfortable.
I gave them to my SO’s grandmother and begged her to fix them in time for an upcoming show. She couldn’t quite patch them or sew them back to the seam because the material is so stretchy. She had a light bulb moment. You know how many breeches have that inside pocket that we usually never use for anything because it’d be uncomfortable/too small? Well she removed that and it made the PERFECT patch. Same stretchy material as the rest of the breech, same color, so less obvious.
Just a friendly suggestion for those looking to patch an inconspicuous area with the same material as your breech (if they’re like mine!)