I have owned two warmbloods that weren't pure breds. My first was a KWPN DWB, and his grandfather was a thoroughbred who was big in Ireland. I now own a registered SWANA SWB, but he isn't even half Swedish. His father (who is registered as a SWB) is 1/4 Hannoverian. His mother is a registered KWPN DWB, but she is half Trakhener and has Westfalian in her as well. Going back to her great-grandparents, there is only one registered KWPN out of 8 (one pair of great-grandparents were both westfalian and got registered as KWPN). She is listed as the "undefeated Top mare of Holland as a yearling, two, and three year old".
I think they were both very well bred, but I certainly wouldn't consider my "SWB" to be a real, pure SWB. It doesn't really bother me because he is such a great horse, but it seems like the lines between the breeds are being blurred with him. In your opinion, how far is too far with introducing new blood to a breed without losing the distinction of the pure breed?
Here is my first horse, he was the registered KWPN but only 3/4 actually KWPN DWB:
My current SWB who is actually less than half SWB (not the greatest of pictures but too lazy to take more):