God, I just love Lois and Clark. Theirloveissosquishyandawesome!
An idea I've been playing around with: If Lois and Clark wanted kids, they actually have several options in-universe. There's genetic engineering (which we know is possible from Kon), or they could ask Diana if she could call in a favor from her patron (or would that be matron?) gods/goddesses. One of them is the Goddess of Fertility, I bet she could do something about that. Or call in a favor from any of the other really powerful entities that owe them favors and might possibly have some influence over that.