[Sweet Apple]

I've been really fortunate not to have dogs living next door to me for a couple of years now.....However, my neighbor's divorced daughter just moved in w/a small'ish adult dog and a boxer about 8-10 months old...I have tried and tried to stop them from fence fighting, to no avail ...I want to be a responsible pet owner (I live in a neighborhood), but I also want to let my pups run in and out, during the day, when the weather is so nice, and I'm home...There's a 6 1/2' redwood fence, so they can't really see each other, but they sure bark at each other, hysterically...Anyone have any suggestions how to remedy this?