Just some of it may not be able to be on the contract itself and instead on a supplement or a bill of sale.

Basically supplements social security.

Ex: Cashflow $500-900 a month (depending on financing) and use that to help supplement part of a $800-1200 mortgage which can buy you a lot of house in some nicer parts of Delco. 

Our goal has been to build cash flow to supplement an income of $3000/mo.

In the supplemental material provided when buying @David Greene's book "Buy, Rehab, Rent, Refinance, Repeat The BRRRR Rental Property Investment Strategy Made Simple" (which I should have in the mail soon), he mentions an operating agreement with your private investors in which their is language that promises them first lien or position.

Having said that, some lenders will allow you to do a supplemental loan on top of assuming the $1MM loan in the above example so you might be able to get back to a 25-30% down deal just like getting a whole new loan.

You can also use BiggerPockets as a supplement.

Are you looking to build supplemental income? 

Supplement cost of owning a home through some rental revenue.

Per what I see it's the same in the KC area as well.As for Facebook - I'm a believer FB live videos and other marketing is a current way to supplement old school ways of simply throwing a property on the MLS and having sites like Zillow and Realtor.com pick it up.