Is Daisy spayed? It is common for dogs that are not spayed/nuetered to become aggersive against other dogs.

I would recommend putting up baby gates to seperate your dogs so they won't fight. Also, give them the same attention, they might become jealous of eachother if you give one more attention them the other.

You should really get a trianer when you have a money. It will make a huge difference in your dogs' behavior.