I am primarily looking for small multi-family houses to house-hack or SFH to fix up and rent.

Then the seller will not fix it because it's big money. 

Even if I cant find the other 2 children.Do I have the right to go ahead and fix the property and rent it out.

 Where in the US can you make the most money fixing houses or buying rental  property?

If you can get conventional financing at a fixed, 30-year rate, that's tough to beat.

Then get a purchase investment 30 year fixed rate mortgage on the investment house(s).

From what it seems you are saving capital to purchase your first flip wholesaling, is the best way to me because that's exactly what am doing building a brand and capital to fix n flip also, buy and hold.   

I continued to look for investors everywhere I went. at street fairs, through my small network of home owners and business people, hosted seminars on finding and doing fix and flips and built up a group of investors who encouraged me to find them development deals. 

Keep in mind  Jacksonville is a different scale of magnitude than other cities.   5,980 Roof  2,350 Siding repair2,950 Ext paint 350 Screen replacement 180 Window screen600 Hot water heater 500 Appliances used 135 lights 450 Bathroom repair2340 floor 1800 floor 1300 carpet in bedroom 375 electric150 smoke detectors350 Ceiling repair 250 Touch up paint 200 Misc caulk 100 sink 125 garage fix 375 plumbing repair 175 Window    21,315 total 

On the other hand, another expert thinks it would be cost prohibitive to find and keep good tenants, even if I fixed it up completely to current standards for the area based on the location.