The earliest mentions I can find of this rose credit Parmentier as the breeder, and not until Otto's 1858 'Der Rosenzuchter' is Laffay credited with this rose.

Looking at the early references, I noticed that 'Jenny Lind' was usually listed with 'Lanei' and 'Nuits de Young'; both of these Mosses were 1845 introductions by Laffay. It seems probable to me that first the breeder was transposed, then the date. The introduction date Otto gives, 1851, is very likely when 'Jenny Lind' was introduced to German nurseries. The earliest reference I could find to the purported 1845 introduction isn't until 1882.

When I first found the 1849 Van Houtte reference crediting Parmentier, I wondered if Laffay had bought the rights from LVH, and introduced the rose to France. I thought I was seeing a not-unusual case where the introducer gets credit for being the breeder, but after reviewing all the references I could find, I doubt Laffay had anything to do with 'Jenny Lind', and that Parmentier deserves long-overdue credit for this rose.

If anyone has seen references that contradict or support this conclusion, I'd love to hear about it.