Nellie, perhaps I was not sufficiently clear initially. I have been drawing on the information in Margaret Vine's paper. So, this is not "my research" to pass along and I have no doubt that the Royal Collection has the information but have not yet amended their information on the web.
M Vine also provided me with the lead to the material in the National Gallery of Australia. She stated that there were two design sketches in the NGA, but only one showed up in the online search. She says there are also 2 designs for the hibiscus brooch but, although they (and possibly a third) appear as entries in an online search, I could not retrieve the images.
The only thing which has come from my research so far is the information relating to Mann's children. Vine does not mention that.