Have you looked for them abroad? At this time many children in care were shipped abroad to Canada or Australia as part if the Barnados Home Scheme.
I am aware of that and Miss Steers home was part of that programme and she was a friend of Dr Barnado. I found an article which suggested that shipping to Canada stopped in the early 1900s. The same article contains the information on the home changing the childrens names. It said these children were shipped without their parents knowledge or permission. I don't think my grans family were split up until around 1910. My Ancestry membership is premium which I don't think gives me access to overseas records. It is something I have wondered about though. Not sure exactly what is available tbh. I do wonder if that may have been a bit late. I would have thought at 17 Charlotte would be already working? The lack of finding anything so far makes it a possibility.
We don't know how my gran got to North Devon but she said she was evacuated during WW1. I didn't know that happened in WW1 but I've done some research and it seems it did occur albeit on a somewhat informal basis. Miss Steers homes closed around 1920.
I have found their names on a few public trees but with no more information than me which suggests they had no luck either. There's one odd snippet my gran did mention. In the early 1970s she did mention a sister Alice. She said that at that time she may still be alive and living in London. I've no idea if she knew the others weren't or what that was based on.