Fair Warning
I watched this film on TCM last night & enjoyed it.
The ethics of her not telling the family beforehand about her condition was a concern to me. She tells the tutor & is about to tell the father until his friend is injured and he has to rush away.
There are people out there who -- without injures -- are simply child-minded or might have some learning disability that was covered up a bit for whatever reason. Before modern testing and everything, they'd just be considered "simple" or something. Still, here -- though it might be somewhat obvious when she hangs out with the family as she does that she might not be totally "normal" -- it was known. And, I think I'm not alone in thinking it was ethical for the mom to tell.
I understand her reasoning, especially given the times where people like the daughter received less respect, and think it will work out given the resources of her in-laws and the clear love of the husband. Still.