Daisy my 8 year old piggy died recently so I decided to get her cage sister Celeste a new friend so she didn't get lonely. Celeste is almost a year old and has always been a quiet, and I thought, submissive pig. So yesterday I got a beautiful little baby girl and called her Lillie. We introduced Celeste and Lillie on the living room floor and all went OK. I put them in the freshly cleaned out cage together and for a while all was peaceful. However, after an hour or Celeste started chasing Lillie who ran off squeaking and bunting her bottom with her nose. There was no tooth chattering or aggressive stances just the chasing and butting. They seem to happily share the little hut, Lillie stays close to Celeste and all was peaceful last night, no squeaking at all. This morning Celeste stayed in the hut entrance watching while Lillie ate and mooched around a bit. Is this behaviour just normal sorting out of dominance? I know they have only been together for 24 hours but for 8 years I've only introduced new piggies to Daisy and she never did any of this. I'm worried Lillie is feeling stressed and bullied, she's such a tiny little pig I feel sorry for her. I've attached a photo of them just after they met.