The Rosettes series followed in the footsteps of older collections of pony stories like the Collins Pony Library. All the titles were originally published by the American company HarperCollins, and most are stories by American authors of teenage girls and their horses. The one exception is Cara’s Dream, the first pony title by British author Diane Redmond.
Six titles in all were published in 1994, but the series was never expanded, and as far as I can see, not reprinted in the Rosettes format. I wonder if the books were picked up in an attempt by Hodder to cash in on the success of the American Saddle Club series by Bonnie Bryant, still going strong at this point.
The Rosettes books, however, lack the vital series element (though the Joanna Campbell and Karle Dickerson titles were tangentially part of the epic Thoroughbreds series: they are supposedly part of Ashleigh’s Thoroughbred Collection, Ashleigh being the heroine of one of the spin off series,) and I presume this is why the series quietly folded.