When Newtall died, the herd and breeding methods were passed to Newtall's son-in-law, Juan Falabella. Juan added additional bloodlines, including the Welsh Pony, Shetland pony, and small Thoroughbreds. With considerable inbreeding, he was able to gain consistently small size within the herd.
After Newtall's death, the herd's management and breeding practices were passed to Juan Falabella, his son-in-law.  Juan then added bloodlines from Welsh ponies, Shetland ponies, and small Thoroughbreds, leading to a consistent reduction in herd size through inbreeding.