Have you heard of NILF?
It might be a good place to start - establishing some rules and boundaries. It's not going to address your specific issue immediately - but I always think it's a good place to start.
Nothing in Life is Free
I agree with the 'time-outs' or separation in times of a major fight. They need to be apart for awhile - while you quickly check for injuries.
OP, I really hope you can get this under control for all of your sakes. I love to watch a little bit of Cesar, Victoria Stilwell - there is something you can take away from all of them. What I learned from Cesar was not so much his poking, prodding, or 'alpha rolling' . . . but that my dogs need
EXERCISE to keep them calm. This was so true - especially for Ringo.
With Victoria - I learned the power of positive reinforcement as a way to train. This helped Ringo's 'strange dog aggressiveness' on our daily walks.
Ringo thanks them both. Lucy came to me as a pretty submissive dog already - which is why she and Ringo work together. If they were both vying for the 'top dog' spot . . then they would be fighting all the time.
And, NO, I'm not sure I'm the top dog in this household!!!