All schools have the right to set their own reply date, just as they can set their own date for when applications are due. You probably lose nothing by asking, but I doubt they'll grant an extension. After all, Smith has other transfer students, who applied by the later deadline, who could have your spot if you're not using it. So you've got to make the decision yourself whether you're ready to commit to smith or not. One option, if it's affordable to you, is to put down your deposit at Smith and then withdraw if you get accepted elsewhere. You'll lose the deposit of course, but you give yourself more time and some protection.