Dave , Mike here - helping you with your gardening on tomatoes and other crop before with lifetime of farm experience behind me.The only thing you need to worry about is that your blackberries are actually blackberries, and not the Jewel raspberries which are actually black. You will not otherwise have a cross pollination across berry species.YOu do however need to be aware that your raspberry plants may "harass" the root systems of blueberries, they tend to really grow out a bit more and blueberries do considerably better undisturbed. Raspberries often encroach. So it would be best to space them just a bit or have the raspberries separated by the blackberries if you really want them tight to each other. This is important if you want them to thrive and is actually different from something like strawberries.