legal obligation?!

We had a lender that had the customer complete the borrower side of a 2nd mtg/home improvement application and the coborrower complete a uniformed residential application on the coborrower's side - both customers signed each of the applications. They both were declined when credit scored. The co having the higher becon score. The lender overrides the loan in the customer with the lower becon score's name only but has both of them sign all of the documents including the Note. What if any is the legal obligation of the person who signed even though her name is not on the Note?

It's a joint application whether it's on one piece of paper or two.
How could the LO do the loan at all if their credit scores were both too low?

They did an override to combine both loans - I had a problem with them making the loan to the customer with the lowest score and not having a declined package on the coborrower. I just wasn't sure if the signature on the loan was enough to obligate the party not listed.