What blows my mind is that there are nice, registered, inspected and jumper bred WB mares with previous careers being given away or free leased for breeding. Kate chose to use these types of mares quite deliberately. I believe she thinks she is reinventing the wheel. What qualifies her to do that, I have no idea.
Also, re: the stallion prospect. In order for the colt to be a stallion prospect, his pedigree must be submitted to the registry for pedigree approval. I cannot think of a single registry outside of American WB that is going approve a half harness, half jumper bred colt. The other route would be performance approval - the horse is competed to advanced levels and approved based on a certain number of scores over a certain percentage. I do not see this colt holding up to either GP jumping or dressage. Important for buyers to realize all of this. Just because Kate thinks the colt is stallion quality, does not mean this is actually feasible.