In the depth of the housing bust, an acquaintance did this. Her in-laws took out a second on their home so the kids could make an all-cash offer on a foreclosure. Place was a dump. They worked their assess off to fix it up. Eventually they got a mortgage and repaid the parents. House has at least tripled in value since then. I don't advise this, but it worked for them.
My concern with the parental route is that it might preclude you from participating in the physician loan program, which sounds like a great deal, on the face of it. My advice is to slow down and wait for that option to kick in. Finding the right house takes time. Also, you might find a proparty that the sellers don't want to move out of right away. I'm not talking about buy/rent-back. For example, we're kind of ready to do another house flip. Our realtor knows of something that meats our parameters, but the owners don't want to sell until February. Win-win.