My go-to method, using DAZ Studio, would be to create and export the parent heads into the same directory in DAZ, then, within DAZ, dial the two "parents" appropriately to create the child.
Within DAZ, there are also youth morphs available to further tweak the "age" of the resulting child head.
If I really want randomness, I'd use SimTenero's RANDOMIZER script and choose the specific "parent" head morphs. (This way, you can even add the 'grandparents' to the mix, assuming all the male/female morphs are in the same directory!)
It's not a 1-click solution, but it works for me.
FelixFFDS