I watched it, that sister is a very attractive healthy woman in her thirties.  She knows what she has to go through and she's just pandering to whatever her sister says.      I think a lot of "enablers" are more like me than most assume.    It comes down to being honest or being in conflict.   Their health isn't worth being in conflict to me.   And that's where this sister comes from.  She has a few cute little "she's healtier than me" stories just to keep the fat cow happy.     Trust me, go enabler.  It's less stress, and the source of the problem goes away faster.