I have 2 girls, 4 years old and I am trying to introduce a new piggie. She is very young, I think about a month. The two adults were the dominant ones in a group of five girls, but we lost three of them this year. One of the adults is lunging her head and possibly nipping or butting the little one. I tried doing bonding time in a neutral space and it seemed to go well. They even took a nap together (all three of them). So I put them in the cage and that's when I saw the lunging/nipping. The little girl is usually just sleeping or eating when the dominant one does this. I'm not sure what is normal or not. The little girl squeals and hides a lot and I feel bad because she is so small. I can tell she wants to just fit in. The second adult doesn't seem to have any problems and doesn't chase her etc, except a couple times.