Hi Flossie and welcome to Lactnet.  I know you are a Lactnut at heart like
all the rest of us!  One experience with premature triplets was that mom's
body seemed to know there were three babies back at the hospital.  Early on
she was getting over 50 oz/day without even hardly trying!  It would make
sense to  me that total # of minutes would need to   be increased in whole
day, but I'm not sure if increasing blocks of time pumping or increasing
frequency is way to   go.  Double pump  for sure.
Hope someone has more info.  Sincerely, Pat in SNJ