This is an interesting thread, I was going to suggest usage of more speedlights until I saw the mention of your family being part of the photos - too much speedlights popping allover can be very irritating!(just not behind the camera!)
You could try another thing to diffuse the lights as well - Point them to the ceiling, than the floor to get more even diffused glow! (you could use lighting fixtures to do that or temp screens etc., I have found that it softens light quite well for portraits.