One I-864 can be used for both people ... make a photocopy and make sure both names are on it.
You can get a copy of your 2010 return and the REQUIRED Tax Return Transcript from the IRS:
Make sure she understands the risks/responsibilities she is taking on for 10 years.
PROFESSOR OF IMMIGRATION LAW for over 10 years -- This blog posting is offered for informational purposes only. It does not constitute an attorney-client relationship. Also, keep in mind that this is an INTERNET BLOG. You should not rely on anything you read here to make decisions which impact on your life. Meet with an attorney, via Skype, or in person, to obtain competent personal and professional guidance.