Due on sale was triggered so what should I do?

[Luis Herna]

Here is the scenario:

A. "Subject To" deal on the mortgage

B. 30% equity is seller financed (to be paid in 10 years) 

C. Lender find out and Due-On-Sale Clause is triggered?.  

Here are the questions

1. How can I refinance so I do not have to return the property to previous owner? .

2. Do I have to refinance with current lender or they will deny any refinancing deal with me?

3. Do I have to put any down payment even thought seller has 30% in equity that he is financing to me?