How is a subordinate mortgage satisfied?

Do you mean paid off? If you are subordinating then they are not being paid off. They are agreeing to be in 2nd position. Meaning, that if you have a 1st and HELOC, if your home goes into foreclosure your 1st mortgage will recieve all monies owed before the HELOC will be paid. If you sell your home and you get over what you owe then the HELOC is paid at that time.