User blog comment:SpookyBoogie27/Light Novel Spoilers/@comment-75.93.25.66-20140129044525/@comment-1359322-20140129082248

Euclid may not consider Grayfia as part of the clan anymore, so he might not view Millicas as his nephew.

As to the Vali situation, Vali is a Devil-Human Hybrid Lucifer not a Pure-Blooded Devil Lucifer, so he might not consider Vali as a true Lucifer.