NEVER LIE TO US IMMIGRATION. The fact that you have stated on a public forum that you would consider not disclosing your actual return demonstrates very serious issues. You need to enlist the services of an attorney to assist in your filings.
You need to also speak with a tax professional. College students are considered "dependent" for financial aid unless they meet very specific conditions. Did you accurately claim your eldest as a dependent?
If you do not want to get a cosponsor, you will need to wait until you meet the income requirements.

