I echo her "Huh?"
Meanwhile, those kids . . . in general I'm kind of with younger sis about loosening up, but frankly a huge loan at 25%--older sis is right, that could eat them up and where are their dreams then? Something like that is a major crisis and you do whatever you can to get rid of it right now before the power of compound interest crushes you. They should take her help if it's on offer; if they want their pride they can pay her back at 3% interest or something.