It is unfair to you, but lots of things are unfair. Singles get a lower asset protection allowance. Singles have a cut off of $80k for full AOTC while married people, whether both work or only one does, have a $160k limit (and then it gradually reduces). Fair for coworkers each earning $100k, one married, one single to have different tax credits on the same income, same college cost? Absolutely. Unfair that the limit is the same whether you have one child in college or 6? Absolutely.
What I don’t think you are figuring in is that at a certain point, it really doesn’t matter if the federal EFC is $15k or $40k or $60k. Once it is about $10k, you aren’t going to get any extra federal aid and the school may have its own forms or require CSS which WILL show the stepparent’s income and obligations for child support. For schools that give really good institutional aid (Williams, Ivies, Stanford) you will have a chance to plead your case on the CSS.
Run those NPCs with 2 students in school and with 1. Are you really getting need based aid that makes up that difference between and EFC of $32k and $64k, or even the difference between $20k and $10k? If you list a few schools he is considering, many on here can tell you how specific schools handle FA. There are definitely schools in the ‘donut hole’ for middle class families and no matter what you do or how many kids you have in college, you just can’t get enough aid for those schools.
I don’t think it is a failed system. Going to college is a privilege, and going to a particular college even more so. The government gives needy students a small amount of money in a Pell grant and allow students to borrow at a low rate. Usually that is enough to go to a public school in the student’s state, but maybe not the flagship. Private schools or out of state public schools charge what they want, give money to whom they want. It they want you, they’ll give you money or set out the terms of how you can get more aid - National Merit, great scores and gpa, athlete, Nobel prize winner. How can you fix that, require all private schools to meet the full need based on FAFSA? Require all schools to cost the same and have the amount set for each student to be the EFC only?
Having said that, I wouldn’t just drop a school before looking into it more. My daughter picked out a school with a COA of $50k+, and wasn’t going to get need based aid. We almost walked away without even asking about finances. The school had merit aid, a few grants, some state grants, and finally an athletic scholarship. All those little amounts made it work without need based aid. I pay a lot more for her sister at a state school, also with no need based aid.
What you are really going to find unfair is if your children have a bio father who will be expected to contribute even if he won’t. That may knock more schools off your list than not getting to count the stepsister.