By feeding the bream you're setting up the situation where the bass are going to key on them for their primary food source. You have two times a day when the bream are concentrated, in the open, and more interested in eating than being aware of their surroundings, in other words, defenseless. This provides the bass with a perfect feeding opportunity that they can not resist. So, when the bass spot a bream that is out in the open and swimming erratically, as it would when hooked, the bass think that the bream feed is on and automatically attack the bream.
By feeding the bream from feeders, you're basically chumming the water for the bass.
So, if you TRULY want to stop this situation you probably will need to stop feeding the bream. BUT, since you have been feeding them for so long that may cause major issues with food availability for the bream which could result in a bream die off, which would result in the bass not having as large of a food source.
Just my cheap two cents.