D3 layouts and family trees

Question

I'm trying to display complex family trees using D3's layouts. What I'd like to end up with is something like this:

    Person 1 = Spouse
                  |
    --------------------------------
    |                              |
 Person 2 = Spouse              Person 3 = Spouse 1 ======= Spouse 2
               |                              |                |
        --------------                        |         --------------
        |            |                        |         |            |
     Child 1      Child 2                   Child     Child 1     Child 2

That is, every second level in the tree behaves like a normal tree, while every other level is laid out differently, with each spouse on the same level.

Is there a way to do this with D3 layouts? Or am I going to have to write my own layout code?