For a family portrait that sounds a good light set up.
One light camera left of right at 45 degrees to the subject and 45 degrees above, I use your silver one here as your main light then the second as a fill light at 45 degree on the other side this time as subject hight. your white shoot through will bounce light all over the place so its best to use that as the fill. the sb600 should give a good balance of light with the silver giving slightly more punch.
as time goes by try playing with turning the power down on the fill then replace the fill with just a reflector and moving the second light behind to create a hair or rim light. or put a color over the second light and point it to the background all add interesting effects
Have a look at some of the bill hunter studio lighting books as he explains lighting very well. youtube is another good place to see lighting setups in action and strobist blog is great just google 'strobist' to find the link
have fun