You didn't ask for any advice, but I will give you some anyways - take it or leave it.
My 4 year old tried to rear on me... a little baby barely off the ground rear. I hopped off, got a lunge line, hooked it to her snaffle and got back on and continued my ride. She tried again, but this time went up. I slid off, smacked the crap out of her ass with the end of the lunge and lunged her as fast as I could make her move for about 10 minutes. They cant rear if they are going forward. She was a foamy, sweaty mess and breathing hard. I got back on and continued my ride. She minded her manners, and has never attempted it again.
Unfortunately, your mare has this maneuver firmly embedded in her bag of tricks, and the faster you deal with it the better. The next time she tries this, and the next, and the next, I would be prepared with a lunge and ready to slide off and make her little butt move hard and fast. The sooner she realizes that rearing will be met with an incredible amount of work, the quicker she'll stop this.
There is no passion to be found playing small - in settling for a life that is less than the one you are capable of living. - Nelson Mandela