We figured out the trick to get her to eat. All good now :)
We don't feed grain in Aussie land - we feed chaff (you might call it chop? It's basically chopped-up hay) balanced with some pelleted feeds, sometimes grains, and suppliments. Satin has chaff and a pelleted feed designed for growing horses, plus a general vitamin/mineral suppliment.
We've had to cut down a bit on the amounts that we're feeding her because she's gotten fat since she arrived (darn good doer part-Arabs!) and I would rather she be between 'slightly ribby' and 'ideal' than between 'ideal' and 'fat' - 'fat' is where she is right now!
She is growing SO fast, I swear in the half-week she's been here she's grown at least an inch at the top of her rump. She's definitely more bum-high than she was when she got here. Having never had a foal before, I'm worried that my reading is right and that any amount of incorrect nutrition, at any age while bubs is growing, is detrimental to the foal's later health and soundness. It's real important to me that she grows up sound and healthy, and STAYS that way as long as possible.
Doesn't really matter either way though, because she IS eating.