A thought I just had, based mostly on my sister's experiences when she had unanticipated twins at 35 weeks, and also on various articles read over the years, but not kept, so I can't cite references:

My sister found when she left the smaller twin in the hospital, both twins stopped eating and fussed alot, sleeping less.  The twin in the hospital was still there due to bradycardic episodes, which increased once her twin left the hospital, as well.  Beverly insisted that twin #2 come home, and both twins improved radically and instantly.  (She took home a bradymonitor and who knows what else, to accomplish this -- that she is an OT at the same hospital gave her an edge that many mothers might not have, as well.)

I have read about separating twins due to illness and prematurity and how they sometimes tend to do worse without their womb-mate.  So taking the older twin to the hospital might be a very important factor in bringing the younger one home sooner?  I like the image of mom carrying the discharged infant in a sling, while kangarooing the one still in the hospital.

Sincerely,  Chanita