My siblings (4 of us) all attended cc after HS, some of us went for 2 years and some for only one. Two of us transferred to private colleges (but one graduated a semester early) one to in state public and one went to OOS public. My folks paid for it and did no accounting as to whose education was the most expensive. The deal was that we would start at the cc and my parents would pay for 4 years of college.
My kids both attend/attended expensive private colleges, however S’s is more expensive because he is 5 years younger and the cost has gone up. D had a small outside scholarship. S turned down several schools which offered him substantial merit. The deal was that we would pay for 4 years of college.
No one did bean counting.