goal is to ensure our clients always know what we do always, and what they must do.

@James MaherA loan is non-recourse when the lender's only security is the property.  

According to the American Land Title Association, the following types of loans do not have to comply with TRID:Home-equity lines of credit Reverse mortgages Mortgages secured by a mobile home or dwelling not attached to land No-interest second mortgage made for down payment assistance, energy efficiency or foreclosure avoidance Loans made by a creditor who makes five or fewer mortgages in a year And, in addition, 100% cash transactions (no lender involved) are also exempt.

You can always put up security cameras that record everyone going in and out. 

When posted the question,  I was more concerned with how easy/difficult it would be to secure conventional loans after having multiple mortgages.  

- they're often used interchangeably, but it is essentially a mortgage insurance premium that you pay each month, in your payment, to ensure the bank or lender gets their money, if you default on the loan.

However, since you expressed an interest in buy and hold as well as flips, I added the links below for your perusal.http://www.biggerpockets.com/renewsblog/2013/01/04/how-to-rent-your-house/ (house rental guide)http://www.biggerpockets.com/renewsblog/2013/02/22/buying-rental-property/ (how to buy a rental property) http://www.biggerpockets.com/renewsblog/2014/01/07/flipping-houses/ (step by step guide to flips)Now that you have made the move, below are some links that will help with the navigation of the site. http://www.biggerpockets.com/startherehttp://www.biggerpockets.com/meethttps://www.biggerpockets.com/alertsHow to Use @Mentions on BiggerPocketshttps://www.biggerpockets.com/ruleshttps://www.biggerpockets.com/inviteshttps://www.biggerpockets.com/forums/categorieshttps://www.udemy.com/biggerpockets-real-estate-investing-course/ (video with 64 lectures and approx 6hrs of material)https://www.biggerpockets.com/real-estate-investing (Ultimate beginner's guide to REI)Before your 1st purchase, please ensure you visit the below link for some tips.https://www.biggerpockets.com/renewsblog/2014/12/19/real-estate-investing-success-smart-tips/REI books suggested by BPershttps://www.biggerpockets.com/renewsblog/2015/11/13/7-real-estate-books-beginner-investors/ (7 absolute must read books for beginner REIs)http://www.biggerpockets.com/renewsblog/2013/04/14/best-real-estate-books/?

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How do I ensure he owns the houses and they aren't still financed?  

You can use your dad and friends money for the downpayment.However please ensure that the deal numbers make sense before even going down any financing road.More specific information would help with providing advice.