Dear Olivier, I have information for you about the family, as I am related.My grandmother was Sarah Olive Child Nixon (b.1885 or 1887), born to George Child Nixon (b. 1853)and Mary Elizabeth Oliver (1854-1939).I was told of a family connection to the Child family, back to Robert by an Aunt. I am still tracing it, but I have visited Osterly Park and picked up a book outlining the family tree.I haven't had time to add it to my tree yet, but will in the next week.
We should collaborate our info.Feel free to e-mail me. I'm delighted to have come across your query.