I thought there was something about moderation and treating them as one class by VCAA because we aren't a large enough class or something...?
I had a similar situation in year 12 doing a subject called Music Investigation - my school had just enough students (as Sine mentioned, 5), but another school didn't. So, the teachers "joined" the two classes so that VCAA could consider the class full for the other school. Tbh, I don't know who the other school was, and I never met the students, because the teachers did things individually still. However, they designed the SACs together, filmed us for presentations, and then would meet up together and decide on marks together so that it was all still fair.
However, what's important to note is that scaling isn't done based on the school - it's based on who's doing the subject. So, yes, you're technically scaled against the other schools - but the only people in those schools doing the subject is one person, so you're being scaled against those people, not everyone else at the school. Similarly, when I did it, I was scaled against everyone in my class, but also the two in the other school - so, I was scaled against the other school, but only the two that did it. There's no point comparing my marks against everyone else's in those schools because even if we shared subjects, we did different SACs, which is the whole point of scaling - to try and normalise the different SACs that every school does.