Can't PM you!! Glad to hear horsie is doing so well on the soaked oats. Really have no idea about barley though. Are you really, really sure she needs it? PF used to react to it as if it were crack!!!
I think you'll be surprised at just how good the oats and alfalfa are at putting weight on!
I've had to cut PF's ration back by a whole kilo (dry weight) as she's doing so well. I understand you being worried about your horse not putting the weight on before winter though. You could try adding sunflower seeds to the oats. They've got lots of oil and the fibre doesn't hurt! PF eats regular sunflower seeds, but the usual type recommended are black oil sunflower seeds which are all black and have softer shells. I feed about a mugful a day, and when I was really worried about PF being skinny (this was pre-oats though) I used to add sunflower oil.