If you buy a home and don't have all the money, you can borrow the portion that you are short on. If you then go to sell the home, you can sell it but must pay off that money you borrowed - the unpaid portion. If the home has gone up in value, you walk away with money in the bank. If you sell that home for less than the mortgage amount because (like now) values have dipped, then you walk from the closing table receiving no money, and may have had to bring money to the closing to get this sold. Some home owners want to sell, but don't have money to bring to the closing table and can't get the bank to agree to forgive them of their debt overage. Their home would sell for less than what they owe on it. Hope this cleared up some issues for you.

To answer your question, a lien that the seller financed mortgage has against the property would keep the owner from selling the home in Florida without first satisfying that lien. Typically a title company or attorney handling the closing for the seller would contact the lien holder and order a payoff amount on the outstanding balance up to the day of closing.

You can sell the house when you want to - just check the pre-payment penalties. Seller financing is like any financing, just read all the details in your loan documents.

Good luck!