As to the first question, yes — you must contact each school and ask to change the form individually. (It might be a good time to strike up a personal relationship with the financial aid office, so maybe they will take special note of your circumstances!)
Honestly, I don’t know the answer to the second question — about hiding assets so your child doesn’t see your full financial picture. I assume there should be a way to “mask” those assets — but Icouldn’t find it at Fafsa.ed.gov.
However, are you aware of these definitions of which assets must be disclosed?
Investments include real estate (do not include the home in which your parents live), trust funds, UGMA and UTMA accounts, money market funds, mutual funds, certificates of deposit, stocks, stock options, bonds, other securities, installment and land sale contracts (including mortgages held), commodities, etc.
Investments do not include the home in which your parents live; cash, savings and checking accounts; the value of life insurance and retirement plans (401[k] plans, pension funds, annuities, noneducation IRAs, Keogh plans, etc.).
Those exclusions might help in this regard!