When misfortunes fall on you, wedding funds are not a priority. So I do not blame the parents. They did not compromise on their daughter's education. Dd2 must understand the current situation. Be happy about her education and that her fiancee and family like her for her and not for what she is bringing. A good relation is what is priceless. Hope her career takes off and she can buy whatever she wishes. Some wise third person needs to talk to this girl and bring her to senses. If the elder daughter can generously gift her sister that would minimize some rift.