They will go to Charlotte's godfather (this is the major consideration for us in choosing their godparents.)
And failing that, they will go to DD2's god parents. (Or rather, who will be her godparents when she is born - but they don't know it yet, cos we are waiting til she is born to ask them lol)

My brother is single as is my sister and neither are in a place to raise a family nor do they necessarily possess the skills/values I would like my daughters raised with. Godfather does, and is much more like us, is stable, has raised 3 children, loves DD to pieces and would be honoured. That is why we chose him.