How can we qualify for a new lower rate, fixed mortgage?

We are a family of 9 (all relatives) living in Grandmas house. We all contribute to the mortgage payment. Grandma has good credit and got a mortgage in 2007 through a mortgage broker under the "loose" regulations. She did not need to prove income. She had to show a city business license. The family’s contribution is made up of employment (taxed), social security and cash (not taxed) sources. We have faithfully paid, are current on the mortgage and have never been late. The current mortgage is at 8 ¼% and we are paying interest only.