So sorry to hear Ralphie didn't make it. I was worried about him, he was so small. There were probably some internal issues, genetic in nature.
Have you tried introducing Walter to the Silkie yet? It would be ideal if the two would bond before you introduce him to the flock. Then if you can, rig a panic room for him with 5 x 7 openings so that he can escape to safety if chased. Place food and water inside for him so he doesn't have to compete for them. Is he about the same size as the Silkie?