Soured dog/cat relationship

[BOB1]

Hi folks I have, what i consider to be, a major problem. Up until this past March, i had two pets, Jack, my Jack Russell, and Patch, my cat. I brought Patch home when he was 5 weeks old, to my dog Jack when he was 3 yrs old. They had been great buddies, in and out of the house, up until March, when i brought home Jill, a part Jack Russell, and part ?, who was 5 months old. Patch the cat, was initially afraid of Jill, and except for sneaking in to eat, she stayed outside. Now, Patch and Jill get along fine, but Jack keeps barking at, and chasing Patch, to the point Patch won't come near Jack, and still sneaks in to eat, instead of her usual ease of roaming around inside. It is going to get very cold/snowy here in the Northeast soon, and i want to solve this problem with Patch/Jack, because she's as much a part of MY family, as my 2 dogs. I don't know what changed in Jacks head, but i need to get things back to what they used to be soon. Any suggestions/help? Thanks. Bob