BU Scholarship versus paid at an Ivy League?

Hi Guys, My daughter just got the fully paid Trustee scholarship at Boston Univ. She has also got in to UPenn, Cornell and Brown. Is an Ivy League education really worth the 200,000 dollars that I will have to pay, as against the full ride at BU? Secondly, any point in asking whether the other colleges would be willing to give some aid based on the fact that she gets the full ride at BU? Someone told me that they might revoke the admission if you bring up this now? Is that even possible?