BOSS will not do much to increase protein content in the diet, but will add significantly to the fat, which IMO is counterproductive most of the year.Along with a crowding issue, you may want to look at feeding dynamics. If the birds crowd around a feeder, there may be a lot of pecking. Some people feed in a gutter or a line on the ground to avoid this to make sure every one gets a fair share. Might be worth observing their behavior at feeding time. I stopped using bowls and feed randomly on the ground, believe it or not, so all birds have options.
If it is protein, BOSS (black oil sunflower seeds) and/or mealworms would add that...
Black oil sunflower seeds will be about 17% protein, 44% fat and 24% neutral detergent fiber (NDF). Striped sunflower seeds will be about 16% protein, 24% fat and 40% NDF.Aug 4, 2014