Having tried adding fruit both ways (during primary, or after) I can say that adding it later preserves more of the fruit flavor.
You can ferment for a week, then rack it to the other LBK that has the fruit already added. Puree it in a sanitized blender, sanitize the LBK, then gently rack the beer (via a sanitized tube or wand) on top of the fruit. No need to stir. Cover and ferment for another 2 weeks.
You can ferment for a week, then rack it to the other LBK that has the fruit already added. Puree it in a sanitized blender, sanitize the LBK, then gently rack the beer (via a sanitized tube or wand) on top of the fruit. No need to stir. Cover and ferment for another 2 weeks.