But the father and son are both dead now and the wife is semi-retired and I am not interested in buying anything in NJ anyway.

Mostly retired folks in the area..not a high end area but definitely not a warzone. 

This is for long term "early retirement" in 15 years investing.1) location (neighborhood, elementary school)2) price3) appreciation potential- I want the rent to appreciate higher than inflation to preserve4) size- I appeal to families.

Just hoping to get your knee jerk reactions to the idea.tl;dr: If I buy a 3 or 4-plex, let my broke retired parents live in it, and AirBnB the vacant units, would that be a net-positive or a net-negative for me?

The ROBS 401k allows you to use/combine personal funds, retirement funds and other investors funds and even financing from third parties to finance your new or existing real-estate operating company.

totally agree with Robert G Jobs is #1, although florida has the retirement "driver" which may not get you any tenants put keeps pressure on housing demand, especially safer (crime wise) communities

I plan on making a bank account for the property and not touching it until I retire from the service.

Keaton"..sorry for the younger members who don't know who that isAgain, I just wanted to say thank you for changing my outlook on retirement and life, but also helping me teach my kids about true economics.

@Jason D.Note that retirement funds can be invested directly into real estate.

Tie it into the normal flow of conversation, for example, when they are talking about being worried about not having enough money for retirement, you can say, "Well I have a plan for that..."