the whole mahabharrat, ramayan, kansha, krishna whatever is just a myth guys....these are just stories made for the entertainment,  for moral values........since there were no other means of entertainment , no  written laws back those days,,,,,,,,,,mahabharat and ramayans might actually have happened, but i am sure not exactly as it is written....so every events on the story might not be true even though the story as a whole might be true................thus there is no point in argueing why kansha put them together ?, why he didnt kill them instead ? ..blah..blah...blah....