I agree that you need to escalate this to the district level. Also ensure you get EVERYTHING IN WRITING. Students studying abroad are a huge pain to schools/districts–they don’t like it at all. You’re not imagining that they’re annoyed. They are. And they’re not going to bend over backwards to help you, so you’ll have to push. Come up with a workable plan, get the agreement in writing (including about those elective credits transferring).
I speak from experience. I also received a (government) scholarship to study abroad for a year, though mine was on a more standard schedule as I was going to Germany. My school could. not. care. less that I got this prestigious scholarship and a once in a lifetime opportunity. They thought I was weird for leaving (they also thought I was weird for going to college out of state two years later. So.), and made things as difficult as possible. We got a verbal promise from the Vice Principal that I would get junior year credit (pass/fail) and graduate on time (provided I made up my junior year American Lit and AP US History credits as a senior, which I did). Well: he left the school while I was gone, it wasn’t in writing. When I came back, a) they really didn’t want me to become a senior and graduate on time. My mom had to fight them hard. In subsequent years, the students who got the same scholarship had to repeat their junior year. b) the district was AWFUL about transferring credit. They converted all my pass/fails (all passes) to Cs. I was a straight A student. My mom negotiated them up to Bs, and it tanked my GPA (I wrote an addendum to all my college apps explaining the situation; my GPA based on actual courses taken in the US for grades was a 4.0 UW). It was just unpleasant all around, and I’m thankful my mom is kind of a bulldog about this kind of stuff (the one and only time in my entire life she acted like a “helicopter,” before that term existed). I also had a single mom, so I can really relate to your daughter 
So: push hard! Set everything up before she goes and get everything in writing. Basically schools/districts are so snowed under dealing with the students they do have (and in public high schools, it’s often too many students, not enough teachers/counselors/admin), that throwing a wrench in the works like this sends them into “no” mode. They’ll tell you no until you offer a workable solution they can live with, and hold them to it. (I worked on the other side, too, finding home & high school placements for exchange students–many many many districts have a blanket “no” policy on exchange students b/c it’s just too much extra work outside the American HS norm)