Since so many of us seem to have serious problems, maybe I should post something more frivolous and upbeat to distract the sufferers and entertain everyone else.
Yesterday I went to groom Penny, but since the weather is colder, the boy is now turning the horses out in the pasture during the day and keeping them in their stalls at night. So when I went to groom Penny yesterday, I knew this and thought how to get around Jasmine's dependence on Penny. Since the accident when I broke my arm/shoulder, I'm paranoid about taking Penny out of a pasture where the horse she's in with will insist on coming, too. And Jasmine is still basically an unknown quantity, so I wasn't sure how hard she'd be to shoo away. I remembered that day she got out of her stall when I had Penny out in the yard -- Did I tell you about that? -- and I didn't want another experience like that. After thinking over the dynamics, I decided the best thing would be to just go into the pasture with the 2 horses and groom Penny. Both horses were loose, unrestrained by anything, so I or they could sort of flow freely around one another, and I needed to be the assertive member of the herd. Penny is bossed by Jasmine, and I know I can boss Penny, but who is the leader, Jasmine or me? That's what we'd need to work out.
I disconnected the electric to the fence so I could climb in with ease. I decided not to open the gate and invite the horses out, when I didn't want them out. But of course, climbing between strands of fencing with horses on the other side might provide challenges of its own, since I would be off balance when doing it. And of course, when Jasmine saw me there, she hurried over to where I was to interact with me. I had to wait till she got some distance away before climbing in. Then I had Penny's grooming kit with me, which I set on the ground, and Jasmine hurried over again to see what it was. I let her sniff the stuff, but when she got nosing around in there, I shooed her away. That was fairly easy.
I could see her mind working: Why is she here? Are we going into our stalls now? What does she want? What's that she brought into the pasture? She usually comes with carrots. I wonder if she has carrots in there. Let's see ... no, no carrots. But the stuff smells like Penny. What does that mean? Will she try to take Penny away from me as she has done before?
Meanwhile, I got a currycomb and brush and headed toward Penny, who was standing some distance off, watching the scene unfold.
Penny was thinking: Here she comes to groom me again. We've done this before, lots of times. Jasmine wants to know about it. What will Jasmine do? Do I stay around for grooming, or stay away from Jasmine?
As I walked toward Penny, Jasmine followed me. I could see when she got close enough that Penny thought of leaving, so that's the distance that I had to keep Jasmine away, I realized. So I turned around and shooed her away. I don't think she understood (or didn't want to) me waving my arms at her and saying to get away. She stood there, saying, "Huh?" I insisted, and she got the message, but soon she'd creep up again, and Penny would start to walk away from me. I repeated the process, getting verbally firmer with Jasmine. She is a smart horse, very interested in interacting and communicating with people (is that from her year of isolation from other horses?), and I like that about her. I even think her nosiness and interest in involving herself in whatever is going on is a good trait, though it can cause trouble when she won't mind her own business.
We continued to work this out till Jasmine got the message enough that I felt comfortable cleaning out Penny's feet. Penny knows to stand still for this, even if she's not tied, but if Jasmine came toward us to drive Penny away from me, then Penny wouldn't stand still. I didn't really want to be under her then. So you know I was fairly sure that Jasmine would keep her distance, and I kept a watch on her out of the corner of my eye, even as I was bent down at Penny's hooves. It worked!
This may sound trivial, but this kind of communication is important when dealing with horses. Horses express the hierarchy by driving a horse away. Jasmine can approach Penny, and she knows to move away, even w/o any threat gestures from Jasmine. Since I was new to the mix, I had to let Jasmine know I could drive her away. In other words, in dog language, I had to be top dog. I could take possession of Penny, and Jasmine had to stand back and let me. Still, I wasn't really taking Penny away. Penny was in the pasture. So this was less threatening but still establishing my power over both of them.
I proceeded to groom Penny, and as usual, since I do it all the time, she took it for granted and stood bored but not terribly appreciative. Meanwhile, Jasmine stood off looking left out of the party. She had that look that said, "Groom me, too! I need attention more than her! Look at me!" When I didn't seem to get the message (Jasmine was saying to herself, "Sometimes humans are really dumb. They need it spelled out for them."), Jasmine rolled to show me: "Grooming. Get it? I want you to do me, too!"
I was chuckling over her efforts to get the message across. She is so communicative, and I really believe that when I talk to her, she understands a lot more of what I'm saying than most horses do.
When I finished grooming Penny, I crawled through the fence, turned the electric back on, put the grooming kit away, then just looked over the gate at the horses. Jasmine came right over, and I decided now I could indulge her, so I rubbed her head, and she showed me all the itchy places that needed rubbing the most. Meanwhile, Penny ignored us.
Finally, I said good-bye to them and headed to the car. Penny raised her head from the grass to acknowledge my good-bye.
Now it won't happen before the 20th.
Great story. You're right. You must be top dog and it sounds as if Jasmine is smart enough to realize that you are if you keep doing what you did. You making Jasmine keep her distance could give Penny more confidence. She may think "if she can do it so can I". 
