Real Estate Community Forum

Ok here is my concern. My brother and sister in law have went into a contract for renting to own, so they are already moved into the home. They spoke with a guy who is selling a house and he said he would do the rent to own. He said for the first 6months all $1500 a month will go towards the down payment and $500 will go for the last 6 months. The agreement would be for 1year. They would only be putting $1500 down payment just like a security deposit. The home is worth like $289,000. I was wondering how its possible for him to give them 100% rent credit? Also if the $13,500 would be enough down payment when they go and try to finace. There credit isnt the best. They have been leasing a car now for a few years but its only in the wifes name. They do have good rental history. She works at a bank part time and as a waitress 1 day maybe 2 days a week. So she works no more than 20hours a week. Her husband works at a gas station making under $11 an hour and works 40 hours a week. They are very hopefull that this will work out for them, but My husband and I are very concerned they are not making a good decision. They have 4 children and we dont want them to end up being homeless or screwing them selves by not being able to afford the mortage if it did go through, so we are gathering all the information we can for them. Any ifnormation of this would be helpful, including would the mortage go down after they get the deed in there name along with what about taxes and home owners insurance? She assumes it will go down.