There are a lot of gaps you need to fill in. Is she an older teacher
who has just had her stability pulled out from under her? Or is she a new
teacher who is not very experience and isn't sure what is expected of her? Maybe
she is a teacher that the district wants to get rid of so they are making her
life difficult, or maybe this is just a matter of expediency for them.
Something similar happened to a teacher in my district some years back.
She was a good teacher who was nearing retirement. It was very upsetting
for her to suddenly be sent part time to another school without even a classroom
of her own, but it was a workable solution for the district so she did not
have much choice. I can imagine someone in that position just taking the path
of least resistance, in other words just assuming the role of a substitute. I
think you should make some more inquiries and try to see where she is coming
from before you get upset about it.
Just be happy that you were not given double size classes or something
of that nature. I have heard of worse situations!