Yes I agree. Why not just be open and honest with her and tell her your plans when you go on mat leave. We can't read minds. Parents expect us to be open and honest with our plans but don't want to give that courtesy back it seems. I agree your provider didn't act in the most professional manner but why not give her a heads up with your plans so she isn't left hanging? This is her livelihood and if she thinks she will have to fill a spot of course she will start advertising, just be open and up front with your intensions.

Also our families come first before our jobs (most people anyways and we are no different). If she decides that her current work hours don't work for her family she has every right to change them.