There have been prior discussions about this (see below), but it might be possible to go back to ‘Little Darling’ while it’s still around to generate new prickle-free lines. It was the seed parent of ‘Smooth Sailing’, which was the matriarch of the Smooth Touch lineage, and it has a number of other prickle-free or nearly so offspring. That trait would certainly be valuable to bring out and preserve in some newer roses with other improvements for future breeding work.