Keep your head up I just had a set of twins born at 31weeks. It was very scary having them that early. They where smaller then your sisters at 3pds 4 oz and 3pds 3oz but there 7 weeks old now an are doing very well. Now days they do amazing things with preemies and the NICU can be a scary place but it became my second hone for the 5 weeks they where there. Ill keep your family in my prayers.
My daughter was 10 weeks early. 2lb 11 oz. stayed in nicu for 8 weeks. Came home on heart monitor stayed on that for 3 weeks. She is 9 months old now and doing wonderful. The Ronald McDonald house is very fabulous. Great ppl worked at the one I stayed at. Stayed there from the time I got out of the hospital till she came home(2days before Christmas) which was about 2 weeks before her due date !! Praying! God does miraculous things.