Re: Horse is being fed "treats" against my will
Sigh, I've been in that same situation. Considering you are describing a barn my BO owned back then... I almost wonder if it is the same person (NoVA). In my case, my horse was a youngster with a weight problem (not yet diagnosed with anything), and only got a tiny bit of sweet feed (1/4 lb) just to keep him happy when his pasture mates were fed. I came back early from a trip to find his feed had been made up with an entire pound of sweet feed! I talked to the BO, she presumably takes to the weekend feeder, who basically refused to feed only what I asked! I ended up having to move him; the offender was a good friend of the BO, and she wasn't willing to do whatever to get this person to stop.
So, you might have to consider finding new accomodations if you cannot get this woman to stop. Take hope though, I found an even better place not far away. If you happen to actually be in the NoVA area, I can recommend a new place, even.
Yankee Case History: https://ecir.groups.io/g/CaseHistory/files/Jodi%20and%20Yankee
Photo Album: https://ecir.groups.io/g/CaseHistory/album?id=54386