How to make my bird to stop attacking....

[renugac]

When I first bought my love birds they were very close to each other. They always help each other when they are itchy and always sitting or standing close to each other. Both are females. After a month one of my birds(chocki) started to be aggressive to lucky. She never lets lucky near and never lets her eat while she is eating. she purposely chases her all the time and never lets her play with the toys. My poor lucky always sits on top of the curtain rod scared and prepared for the next attack. What do I do for this behaviour? How do I tame chocki? Chocki also bites when I try to hold her. she is very aggressive to me also all the time except when she was sick :(
-Renuga