No they are not just being pissy, sometimes the 2 new ones are with each other, it does last just a minute, Muffin and Cookie were like that too, mostly Muffin, but they were friends and were close... but this is different, they are scared of her.

Yes I am sure it's not play, not on their part at least, there is a big difference.

I know it can take a while, Muffin and Cookie were friends after just a few days, Cookie was just 10 weeks old, and Muffin accepted her pretty fast.

I am just going to have to separate them for a while then try again

Muffin is not chasing them to let them know shes boss, she is trying to play, but they get scared.