I'm no behavioral expert for sure but.....that's exactly how Delilah acts when she has one of her toys and sees Daisy coming towards her. I have to take the toy and hide it from her. She acts like she wants to attack Daisy in a hateful way. I don't know if she's trying to protect/defend the toy or defend the area. Or, is she just wanting to be mean to Daisy at that particular time? That's the only time she gets aggressive with her sister. I always think D and D have issues with who has the higher rank between the two of them. Daisy was here first and Delilah is pretty bossy anyway. Maybe Natasha is trying to be the top dog of the Bichon pack?? I'm very illiterate with these things.

Best of luck with the situation, Sandie.