Something you imply as being recent. She said nothing of note regarding the twins during her last stay in hospital. What you're referring to occurred during her first stay.
There's no getting away from it but the psychiatrist hadn't taken Sheila seriously enough. If someone told me that " they were afraid they would kill the children " I'd take it seriously, wouldn't you ? Especially from the point of view of a professional person ? Whenever it was said. The fact of the matter it was said at a mental health clinic for God's sake---which was all the more reason to be aware.