Fed only after the baby is completely weaned. I give dehydrated apple slices or papaya.
If you can't find cranberry juice, you can also give apple juice. Try to give juices with no or very little added predervatives/suger.
Basically, their pellets are alfalfa based. Hence i do not feel it is neccessary to feed alfalfa hay. However, if you notice the mother chin losing weight, do feed alfalfa. Remember to feed timothy also. Critical care from oxbow would also be a good thing to give the mum if she loses weight rapidly while lactating. I try not to feed too much alfalfa due to bladder stones....
Try to handfeed if your chin gives birth to 3 or more. Also, if the baby is underweight. You can mix tge milk with baby cereal..The average weight of a baby is between 45g and 50g if my memory is not failing me.
I'm also writing this from memory and personal experience. Hope this helps.