I will look at an area's housing supply before I decide to flip in that area.

I would structure as a 12 month deal with (2) extensions. 

You may want to have a handyman or plumber separate the supply to the units and allow you to shut off water to each unit separately.

But soon as I save enough cash for 25% down ill buy again, problem is it will take me a year to save up again.I have friends and family that want to invest, I just don't know how to structure the investment.

Do you see any costly structure issue?

@Jasper Cooper There may be some things that could be implemented along the lines that you suggest, depending on how your real estate investments are currently structured.

How should I structure this deal with my father?

For example, if the stairs to the attic are too steep or narrow, they'll need to be ripped out...that's major structural work...thousands and thousands of dollars.And for what?

In addition to the above commentors, If this does become a serious issue, there is one advantage, housing prices will decrease as demand decreases (and therefore supply increases).

As long as everyone benefits I dont see why living in a different market would have any influence aside from it being structured a little different (how they are paid, communication, contracts drafted/signed etc.)I have thought about turn-key investments however I don't believe that will give me much experience at all considering I would most likely be buying it right before it hits the market.