He said we can use a 3rd party send them the monthly checks and they will pay off the loan which is 20-30 a month.

The sad part is we probably agree on a heck of a lot more then you might think.  

They can only do what ALL parties agree to when it comes to funding or transfer of money.

There will always be motivated sellers, the hard part is contacting them and convincing them that you are the person they need to help them.

Sometimes that will flush out something that a seller just isn't quite ready to sell for a few years and it can be a good win/win for both parties. 

All parties have joint liability, giving responsibility for the full amount of the obligation to each party.

Order an appraisal through a third party.

Hardest part is getting started then it's hard to stop...

My partner and I are looking into a 4-unit property where one party would actually live in one of the units in order to get better financing and a lower down payment. 

As a landlord: If the income was sufficient to pay the rent, and all parties agreed to this and signed a contract, and then payments fell behind only because they were forgotten and for no other reason, then the money to catch up on the rent should be there and used as such immediately.