Your tax return only lists one address, it is the address where you want to get tax related mail from the IRS, and does not have to be the address where either of you lives.
I don’t know enough about the current financial aid rules to know whether it would really be harmful for you to only have one address on your tax return, but the only way to list two separate addresses for yourselves would be to file as married filing separately. Under married filing separately, each spouse files a separate return listing only their income and deductions. Married filing separately almost results in a smaller refund or more tax owed because many deductions and credits are limited or disallowed.
since you have already filed jointly, you would have to file an amended tax return to change to married filing separately, and this can only be done before the filing deadline, which is July 15 this year. To change to married filing separately, the spouse who is listed first or on the top line of the joint return will file an amended return changing their status to married filing separately, and remove all of the spouses income and deductions. The spouse who was listed second will file an original tax return as married filing separately, not an amended return. Both the amended return for spouse number one in the original return for spouse number two will have to be mailed. They can’t be e-filed. You will need to get them in the mail before July 15.
Please also be aware that if you change to filing as married filing separately, you will be ineligible for any education credits on your tax return--so be careful when you decide what you are doing.
Your LEGAL address and the one you enter on the tax return for mailing purposes have nothing to do with one another. Many students use the parent's address on the tax return since they do not have a permanent address elsewhere since they often move each school year sometimes more than once. This is normal and doesn't affect the student aid situation. Contact your school(s) financial aid dept to answer all FASFA related questions.