Sorry I didnt see this sooner. I would treat the posing same as any other group posing. You layer them and make triangles for more traditional shots, and spread them out more linear for more contemporary shots.
I'll explain the triangle thing: A good
composition has triangles in it. That's the short version. The more, the better. Take the family and vary their heights in the portrait and layer the triangles.
Example: group mom, dad, kid, and baby together. A patriarchal set up would have dad at the top of the triangle with mom of to one side, baby on her lap, and kid flanking her other side.
Here's an old example with more people. I put this one up so you can see it. For simplicity purposes, I didnt assign the toddler to the front left corner her own triangle, but she could have her own, and she is also included in the mother's triangle. Notice how the pose is creating the triangles. Arm placement is important. In case that's greek, I drew it on there for you.
