How about finishing the tops for the two you already have going first. Then sandwich them and tie them or SID. Add the binding and that's that.
I don't think it's a good idea to mix Sodokus since they depend on correct placement.
As for the babies:
How about making a gender neutral quilt for the babies. Or find out what color the nurseries will be and use that as a guideline. That way you can buy any extra fabric when you find it on sale. You could even make two of the same.