Wolf,
I don’t know exactly where on the spectrum of yeshivos your son is attending. If it is one that is saying that they have to continue in beis medrash you can do what my parents did. They told the yeshiva that we respectdully disagree, if you maintain that my son has to continue in beis medresh, he is all yours except for th ehours I expect him to be in college learning a trade, since that is my obligation towards him. I received some goernment grants and a 3rd party scholarship that went to the yehsiva and my parents didn’t pay.