Many mothers breastfeed frequently throughout pregnancy and beyond.  Unless the mother's medical advisor has advised that she avoid sex, there is no reason to avoid breastfeeding (or expressing).  Virginia Thorley has some personal experience of increasing breastmilk supply very quickly and very intensely while pregnant and in a very stressful life-threatening situation.  
I have worked with mothers to initiate a full breastmilk supply capable of sustaining an infant on that breastmilk alone.  I have no doubt that this mother will be able to meet at least the bulk of her baby's breastmilk needs - and, assuming there are no other issues with mum or fetus, to carry the baby to term.  Once the new baby is born, there will be plenty of milk for everyone.  As for having 2 babies less than nine months apart, I hope she has plenty of support - she won't have time for palaver that comes with preparing and feeding infant formula.
Nina Berry
Australia

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