Try role reversal. Move to Lakewood and have the kids support you. I have news for you. I did not support my kids and when my third married child bought his house and my friend called to give me mazal tov, I told her what is the mazal tov for? I have 3 kids with mortgages I am never going to sleep again!!!!!!!!!!!! And don’t think we didn’t go through the wringer 2 years ago when the economy crashed. Two of my kids were at risk of losing their homes. Its no joke. B”H they are back on their feet again, but for a long time we were very, very scared.
There is nothing you can do but let them suffer through it. You can’t spread yourselves so thin that you will go into debt or put yourselves into an early grave. If they can’t afford it they can’t have it. Let them learn to deal with it and stop looking at what others have. “Live the Torah life and don’t be mekaneh other people. If Hashem wanted you to have what they have he would have made you them and them you.” Tell them to get chizuk from the Rosh Yeshiva or be mispallel for what they want.