Legal Question in Business Law in Maryland

No. When you co-sign a loan, you open yourself up to the possibility that the person who is on the loan won't pay. The only thing that happens in this circumstance is that the lender comes after you AND your sister (it doesn't matter to the lender who ultimately pays). Unless you have a separate contract with your sister, which I'll assume you don't, you are out of luck and have learned a VERY valuable but tough lesson about co-signing. DON'T EVER DO IT AGAIN.

Best of luck.********The above is for informational purposes only and does not create an attorney-client privilege.*******