I totally understand how frustrating it is to work so hard preparing healthy meals and have DCKs turn their nose up at it. I have the same issue every day with one as well (in fact I saw a picture on FB recently of that family @ Christmas dinner...all of their plates loaded full of great holiday food...this 3 year old (& his 10 year old sibling) had just Kraft Dinner in front of him). I have worked very hard and have actually gotten him to just try a bite of what's put in front of him, after which about 70% of the time he does eat it. Please please do not start offering her crap. It's our job to offer (tiny serving so it's not so painful to see being thrown out) healthy food, their job to actually eat it. IF you start making the processed stuff then the rest will want exactly what she's having...you so don't want that.
I would also be very honest with the family as to how much (or little) she's eaten.