Looking for answers...

This past weekend we were visiting family down in Texas and had a great time of it. We've always tried to include Lucy in on our trips whenever possible and she is a great traveller. The weekend was absolutely perfect until we arrived at our daughter Lauren's house on Monday before our scheduled return time. Lucy was in great spirits and doing fine, getting along with everything that came her way until we met up with her former family member Maddy the Boxer dog...

Maddy and Lucy grew up together in the same home for the most part. Actually, Lucy was about 6 months old when we first got her and Maddy helped Lucy join the family. They got along great until Lucy became taller than Maddy. One day they got into a dispute over by their feeding area. Neither of the two dogs backed down, and you guessed it, they got into a fight. Now this behavior has become a common occurrence when they get together.

My problem is, I don't understand why one dog is trying to dominate the other? They both have the same privileges, care and attention. Could their behavior be due to them both trying to establish the Alpha role? Other than keeping the dogs separated is there a technique that can be used to help them get through this behavior when they see each other? Or would it be best just to keep them permanently separated from one another? Help...