I have never followed up on the jewels of the Rosse family, so I was interested to read your article and to learn that you think the parure is still with the family. I had assumed that the modern photos of the tiara might have meant the parure was auctioned at some time -- I assumed that was probably to pay for death duty taxes. Great to know that is not the case.
Lord Snowdon's mother at the 1937 coronation (the only image I have of these jewels)
One thing I would venture to say is that I don't think all these emerald jewels were a parure originally. Stylistically they do not match, but I am sure that together all the jewels make a splendid sight.