Congrats on the new one. I dont get the secret part. Like, why you couldnt tell that your mare foaled ?
I like Sally,
what legs, wow.

FYI, I would take precautions to allow a mare to foal by herself. Other mares will just usually crowd around and can really get in the mares way. I also have mares that will go through a fence with hot wire to steal a new baby....they want it so bad. Good-Luck !