I'm going to take too long to change clothes and make my sisters late for school
Did your sisters do something wrong? Are you doing this on purpose?
I am.
It wouldn't be right for your sisters should to experience negative consequences thanks to your actions.
Who said it's their problem?
Well, making them late for school is definitely going to be their problem and they may get reprimanded. Your sisters see you as a role model and that sort of behavior isn't the kind of thing they should imitate, so I hope you reconsider and try your hardest to be the best sibling you can be.